What is the difference between gray and grey?

Gray and grey are two spellings of the same color, with gray being the standard American English spelling and grey the standard British English spelling, so the choice depends entirely on your audience's location.

Is gray or grey the correct spelling?

Both gray and grey are correct spellings, but gray is the preferred form in American English while grey dominates in British English, so neither version is grammatically wrong in any context.

Which spelling, gray or grey, is better to use?

The better spelling is gray for American readers and grey for British readers, so you should match your spelling to your primary audience's regional convention rather than choosing a universally superior option.

Does using gray or grey affect the cost of printing or design?

No, the spelling choice between gray and grey does not affect printing or design costs because both words represent the same color value and require identical ink or pigment amounts.

Are there any safety or risk issues with mixing gray and grey in writing?

Yes, mixing gray and grey in a single document creates a consistency risk that can distract readers and reduce your perceived professionalism, so you should pick one spelling and use it throughout.

How does gray versus grey compatibility work with style guides?

Gray is the required spelling in American style guides like APA and Chicago, while grey is required in British guides like Oxford, so your choice must align with the specific style manual you follow.

What is the most common beginner mistake with gray and grey?

The most common beginner mistake is using grey for American audiences or gray for British audiences, which immediately signals a lack of regional awareness and can undermine your writing's credibility.

Can gray and grey be used interchangeably without changing meaning?

Yes, gray and grey are fully interchangeable in meaning because they describe the identical color, so swapping one for the other never alters the substance of your message.

How do gray and grey apply to real-world use cases like paint or hair?

In real-world use cases, gray is the standard spelling on American paint cans and medical charts for hair color, while grey appears on British products, but both refer to the same visual shade.

Can I switch from using gray to grey in the middle of a project?

You can switch from gray to grey mid-project, but doing so creates avoidable inconsistency, so it is safer to finish with your original spelling unless you are revising the entire document for a new regional audience.

Difference Between

Difference Between Gray and Grey

Written byNex Virox Team

Editorial Team

Reviewed byVarshal Nirbhavane

Senior SEO & Organic Growth Professional · 5+ years

Published: August 25, 202620 min read

Quick answer

The main difference between Gray and Grey is that they are two spellings of the same color, with no difference in meaning. Gray is the standard spelling in American English, while Grey is the standard spelling in British English. Both are correct.

Key takeaways

Spelling location: Gray is the standard American English spelling, while grey dominates British English.
Regional usage: American publications use gray, but grey appears in UK, Canada, and Australia.
Proper nouns: Grey stays fixed in names like Greyhound and Earl Grey tea, regardless of region.
Best practice: Match your audience's locale; use gray for US readers and grey elsewhere.
Common mistake: Mixing both spellings in one document signals inconsistency and weakens professional credibility.

Table of Contents18 sections

Difference Between Gray and Grey: Comparison Table

Aspect	Gray	Grey
Definition	Standard spelling in American English for the color between black and white.	Standard spelling in British English for the identical color between black and white.
Purpose	Serves as the accepted orthographic norm for all U.S. government and educational documents.	Serves as the accepted orthographic norm for all U.K. government and educational documents.
Core Mechanism	Spelling convention governed by American dictionary standards, chiefly Merriam-Webster.	Spelling convention governed by British dictionary standards, chiefly Oxford English Dictionary.
Origin	Traces to Old English grǣg, later standardized with an 'a' by American lexicographers.	Traces to Old French gris, adopted with an 'e' in British usage during the 20th century.
First Use	Appeared in American texts consistently from the early 19th century onward.	Appeared in British texts consistently from the early 20th century onward.
Geographic Scope	Dominant in the United States, covering approximately 330 million English speakers.	Dominant in the U.K., Ireland, Australia, New Zealand, and Canada, covering roughly 150 million speakers.
Dictionary Status	Listed as the primary spelling in American Heritage and Merriam-Webster dictionaries.	Listed as the primary spelling in Oxford and Cambridge dictionaries for British English.
Regional Variant	Preferred in American English; also standard in Philippine English academic writing.	Preferred in British English; also standard in South African and Indian English publications.
Spelling Rule	Follows the American pattern of simplifying -ey endings to -ay, as in 'grayhound'.	Follows the British pattern of retaining -ey endings, as in 'greyhound' and 'greybeard'.
Pronunciation	Pronounced /ɡreɪ/ in American English, identical to the British pronunciation.	Pronounced /ɡreɪ/ in British English, with no phonetic difference from the American form.
Frequency	Appears in American corpora at a ratio of roughly 10:1 over the 'e' variant.	Appears in British corpora at a ratio of roughly 10:1 over the 'a' variant.
Search Volume	Receives higher query volume in U.S.-based search engines and local SEO results.	Receives higher query volume in U.K.-based search engines and local SEO results.
Autocorrect	Default replacement in U.S. English keyboard settings on iOS, Android, and Windows.	Default replacement in U.K. English keyboard settings on iOS, Android, and Windows.
Grammar Checkers	Flagged as correct by Grammarly and Hemingway when the document language is set to American.	Flagged as correct by Grammarly and Hemingway when the document language is set to British.
Scientific Use	Used in American journals for units like gray (Gy), the SI unit of absorbed radiation dose.	Used in British journals for the same SI unit, spelled gray, not grey, per international standard.
Proper Nouns	Appears in American names like Gray's Anatomy, a standard U.S. medical textbook.	Appears in British names like Grey's Anatomy, the TV show, and Earl Grey tea.
Color Code	Maps to hex code #808080 in both American and British web design standards.	Maps to hex code #808080 in both American and British web design standards.
Brand Usage	Adopted by American brands like Gray Goose vodka and Gray & Davis law firm.	Adopted by British brands like Grey Goose vodka in Europe and Grey London ad agency.
Publishing	Required by the Chicago Manual of Style for all U.S. book and magazine publications.	Required by the Oxford Style Guide for all U.K. book and magazine publications.
Education	Taught as the only correct form in U.S. elementary spelling curricula.	Taught as the only correct form in U.K. primary school spelling curricula.
Legal Docs	Mandatory in U.S. federal court filings per the Bluebook citation standard.	Mandatory in U.K. court filings per the Oxford Standard for Citation of Legal Authorities.
API Default	Returned by American spell-check APIs like LanguageTool when locale is set to en-US.	Returned by American spell-check APIs like LanguageTool when locale is set to en-GB.
Historical Trend	Gained dominance in America after Noah Webster's 1828 dictionary codified the 'a' form.	Gained dominance in Britain after the 1906 Oxford dictionary standardized the 'e' form.
Ambiguity	Creates no ambiguity in American English; readers accept only the 'a' form as correct.	Creates no ambiguity in British English; readers accept only the 'e' form as correct.
Code Switching	Used by American writers who switch to 'grey' only for stylistic or poetic effect.	Used by British writers who switch to 'gray' only for American audience targeting.
Translation	Rendered as 'gris' in Spanish and 'grau' in German by American localization teams.	Rendered as 'gris' in Spanish and 'grau' in German by British localization teams.
Typing Speed	Requires one less keystroke on QWERTY keyboards, a negligible 0.01-second difference.	Requires one extra keystroke on QWERTY keyboards, a negligible 0.01-second difference.
Accessibility	Recognized by U.S. screen readers with identical phonetic output to the 'e' variant.	Recognized by U.K. screen readers with identical phonetic output to the 'a' variant.
Best-Fit Scenario	Choose for U.S. audiences, American publishers, or any en-US locale configuration.	Choose for U.K., Australian, or Canadian audiences, or any en-GB locale configuration.

What Is Gray?

Gray is a neutral color created by mixing black and white in varying proportions. It exists to provide a balanced, subdued alternative to pure black or white, offering depth, sophistication, and versatility across design, fashion, and industrial applications.

Definition of Gray

Gray is an achromatic color with zero hue and saturation, positioned between black and white on the lightness scale. Its appearance depends entirely on the ratio of reflected light, ranging from near-black charcoal to near-white silver across the visible spectrum.

Key Characteristics of Gray

Characteristic	What It Means in Practice
Achromatic neutrality	Contains no hue, so it pairs with any color without clashing or competing for visual attention.
Lightness variability	Spans from 10% to 90% reflectance, enabling subtle gradients from shadow to highlight in one palette.
Temperature flexibility	Can appear warm with brown undertones or cool with blue undertones depending on surrounding colors.
High contrast pairing	Creates strong readability when used with white text or black backgrounds in user interfaces.
Camouflage utility	Blends into urban, rocky, and metallic environments, making it standard for military and tactical gear.
Photographic neutrality	Used as a gray card reference to calibrate white balance and exposure in professional photography.
Emotional restraint	Conveys formality and seriousness, making it dominant in corporate branding and legal attire.
Dirt resistance	Hides dust, smudges, and wear better than white or black, extending the visual lifespan of surfaces.
Scale permanence	Does not fade noticeably under sunlight compared to saturated pigments, ideal for outdoor architecture.
Print reliability	Reproduces consistently across CMYK and grayscale printing without color shifting or banding artifacts.

Common Examples of Gray

Gray Wolf – a wild canine whose coat ranges from silver-gray to grizzled dark gray for tundra camouflage.
Gray Squirrel – a tree rodent with gray fur that blends into bark and urban concrete environments.
Gray Whale – a marine mammal with mottled gray skin covered in barnacles and white patches.
Gray Matter – brain tissue containing neuronal cell bodies responsible for processing information and muscle control.
Gray Goose – a waterfowl species with pale gray plumage and a pink bill, ancestor of domestic geese.
Gray Granite – an igneous rock with speckled gray quartz and feldspar used for countertops and monuments.
Gray Flannel Suit – a classic business garment made from soft wool blend, symbolising mid-century corporate culture.
Gray Paint – a neutral wall coating widely used in modern interiors to create calm, minimalist backdrops.
Gray Iron – a cast iron alloy with graphite flakes, valued for machinability and vibration damping in engine blocks.
Gray Seal – a large marine mammal with a thick gray coat and distinctive snout found across the North Atlantic.

Advantages and Limitations of Gray

Advantages	Limitations
Pairs effortlessly with every color, making design coordination simple and error-proof.	Can feel flat or lifeless when used alone without texture, pattern, or accent colors.
Hides dirt and wear effectively, reducing maintenance frequency on floors and furniture.	Absorbs and retains heat in direct sunlight, making dark gray surfaces uncomfortably hot outdoors.
Provides a professional, serious tone suitable for legal, financial, and government contexts.	Reads as dull or depressing in large quantities, especially in poorly lit interior spaces.
Works as a neutral backdrop that makes brighter accent colors appear more vivid and saturated.	Offers low visual stimulation, which can reduce engagement in marketing materials aimed at impulse buyers.
Matches virtually any existing wardrobe, simplifying clothing selection and reducing shopping errors.	Shows every lint, pet hair, and dandruff flake prominently on darker gray fabrics.
Creates a timeless aesthetic that resists fashion trends, protecting long-term design investments.	Fails to convey warmth or approachability, creating emotional distance in customer-facing branding.
Improves readability of white text in digital interfaces due to sufficient contrast ratios.	Lacks the energy needed for children's products, food packaging, or entertainment branding.
Offers excellent UV stability, resisting color fading better than most saturated pigment systems.	Can appear muddy or dirty when mixed poorly with other colors in paint or dye applications.
Provides a neutral reference point for calibrating cameras, monitors, and printing equipment accurately.	Offers poor visibility in low-light conditions, creating safety hazards for vehicles and road markings.
Works across genders and age groups, making it a universally acceptable choice in shared spaces.	Cannot convey strong brand personality or differentiation when competitors also default to gray palettes.

What Is Grey?

Grey is a neutral color created by mixing black and white in varying proportions. It exists as a mid-tone between extremes, providing balance, sophistication, and a practical base for design, fashion, and industrial applications.

Definition of Grey

Grey is an achromatic color with equal or unequal luminance from black to white, lacking strong hue saturation. It is a spectral neutral, formally defined by color science as a point on the grey axis where chroma approaches zero.

Key Characteristics of Grey

Characteristic	What It Means in Practice
Achromatic neutral	Grey carries no dominant hue, making it pair seamlessly with any other color in a palette.
Luminance variable	Grey ranges from near-black to near-white, offering dozens of usable shades for contrast hierarchy.
Low saturation	Grey absorbs attention rather than reflecting it, so it recedes visually behind brighter subjects.
Psychologically calming	Grey reduces visual noise and cognitive load, which suits corporate offices and hospital interiors.
Temperature neutral	Grey can lean cool or warm depending on undertones, but it never reads as hot or cold.
High versatility	Grey functions as a background, text color, border, or accent without clashing with other elements.
Dirt resistant	Grey fabrics and surfaces hide minor stains and dust far better than white or black equivalents.
Formal connotation	Grey signals professionalism and restraint, which is why business suits and legal documents favor it.
Light reflective	Grey surfaces reflect moderate light, reducing glare while maintaining visibility in workspaces.
Timeless quality	Grey does not follow fashion cycles, so grey products remain visually current for decades.

Common Examples of Grey

London Fog – a light grey weather condition that blankets the city, reducing visibility to under 200 meters.
Grey Squirrel – an invasive North American species that displaces native red squirrels across the UK.
Grey Goose Vodka – a French premium vodka brand named for its grey-toned bottle and marketing prestige.
Grey's Anatomy – a long-running medical drama television series that popularised the spelling in American media.
Greyhound Bus – an intercity coach service whose grey-painted vehicles and greyhound logo define its identity.
Grey Matter – the cerebral cortex tissue responsible for processing information, named for its greyish appearance.
Grey Heron – a large wading bird with grey plumage, common across European wetlands and riverbanks.
Grey Poupon – a Dijon mustard brand whose grey label and jar design signal upscale condiment status.
Grey Whale – a baleen whale with grey mottled skin that migrates 10,000 miles between Baja and Alaska.
Grey Scale – a photographic and digital imaging term for monochromatic tones from black through grey to white.

Advantages and Limitations of Grey

Advantages	Limitations
Grey hides wear and tear on floors and upholstery, reducing visible maintenance costs in public buildings.	Grey can feel emotionally flat and depressive in windowless rooms, lowering occupant morale over time.
Grey provides a neutral canvas that lets brighter accent colors pop without competing for attention.	Grey lacks the warmth of beige or cream, so it can make a space feel cold and institutional.
Grey works equally well in formal business attire and casual streetwear, offering wardrobe flexibility.	Grey is overused in tech and finance branding, making grey-heavy designs look generic and unmemorable.
Grey paint covers existing wall colors efficiently, requiring fewer coats than vivid hues for full opacity.	Grey absorbs less heat than black but more than white, making grey roofs inefficient in hot climates.
Grey text on white backgrounds meets WCAG contrast standards more easily than many pastel alternatives.	Grey is a poor choice for safety signage because it lacks the urgency of red, yellow, or orange.
Grey suits all skin tones in fashion, making it a safe purchase for online shoppers who cannot try items.	Grey food packaging suppresses appetite cues, which reduces product appeal in supermarket retail displays.
Grey concrete and asphalt provide durable, low-cost surfaces for roads, pavements, and industrial floors.	Grey concrete and asphalt absorb urban heat, contributing to the heat island effect in dense cities.
Grey is a standard choice for office partitions and cubicles, creating a uniform, distraction-free workspace.	Grey office partitions can feel soulless and monotonous, reducing creative energy in collaborative teams.
Grey camouflage works well in urban environments, helping military vehicles blend into concrete landscapes.	Grey camouflage fails in natural terrain, making personnel visible against green foliage or brown earth.
Grey hair dye offers a low-commitment way to experiment with silver tones without permanent bleaching damage.	Grey hair dye fades fastest of all shades, requiring touch-ups every two weeks to maintain the tone.

Similarities Between Gray and Grey

Shared Aspect	How Gray and Grey Are Alike
Core Definition	Gray and grey both name the identical neutral color positioned between black and white.
Color Category	Gray and grey both belong to the achromatic color family lacking hue and saturation.
Primary Purpose	Gray and grey both serve to describe the same visual appearance of a color.
Meaning Conveyed	Gray and grey both communicate neutrality, balance, sophistication, and a subdued mood.
Spelling Function	Gray and grey both function as correct spellings of the same English color word.
Pronunciation	Gray and grey are both pronounced identically as "gray" in all English dialects.
Etymological Root	Gray and grey both derive from the same Old English word "grǣg".
Grammatical Role	Gray and grey both operate as adjectives, nouns, and verbs in English grammar.
Part of Speech	Gray and grey both describe nouns and can name the color itself.
Visual Reference	Gray and grey both point to the same physical color value on any color chart.
HEX Equivalence	Gray and grey both represent the identical HEX code #808080 in digital design.
RGB Value	Gray and grey both use the same RGB value of 128, 128, 128.
CMYK Output	Gray and grey both print using equal black ink percentages in CMYK process.
Design Usage	Gray and grey both serve as standard background and text colors in web design.
Fashion Context	Gray and grey both appear as classic neutral staples in clothing and accessories.
Interior Design	Gray and grey both function as versatile wall and furniture colors in rooms.
Artistic Medium	Gray and grey both mix from black and white pigments in paints and inks.
Photography Role	Gray and grey both appear in grayscale images and monochrome photography prints.
Hair Description	Gray and grey both describe natural hair color that emerges with aging.
Weather Term	Gray and grey both describe overcast skies and cloudy, dull weather conditions.
Animal Names	Gray and grey both appear in common names like gray wolf and grey squirrel.
Figurative Use	Gray and grey both express ambiguity, as in "gray area" or "grey zone".
Emotional Tone	Gray and grey both evoke feelings of calm, sadness, or formality in writing.
Cultural Symbol	Gray and grey both symbolize wisdom, age, and practicality across cultures.
Brand Usage	Gray and grey both appear in corporate logos like Grey Goose and Gray Goose.
Translation Output	Gray and grey both translate to "gris" in French and "grau" in German.
Dictionary Entry	Gray and grey both appear as headwords in all major English dictionaries.
Spelling Checker	Gray and grey both pass spell-check software when configured for their region.
Regional Acceptance	Gray and grey both receive official acceptance in their respective English dialects.
Long-Term Usage	Gray and grey both persist as standard terms with no sign of falling out of use.

Gray or Grey: Which Should You Choose?

Your location decides the correct spelling. American English uses Gray with an "a", while British English uses Grey with an "e". If you write for a US audience, choose Gray. For UK, Australian, or Canadian audiences, choose Grey. This one geographic rule settles the debate for most writers.

When to Use Gray

Choose Gray when writing for American readers or US-based publications. Use Gray in US school assignments, American business documents, and content targeting US search engines. Also use Gray for proper names like Gray's Anatomy or the unit of measurement "gray" (Gy) used in radiation science, which is standardized globally.

When to Use Grey

Choose Grey when writing for British, Australian, or Canadian audiences. Use Grey in UK school work, British newspapers like The Guardian, and content targeting UK search engines. Also use Grey for proper names like Grey Goose vodka or Earl Grey tea. International organizations outside North America consistently prefer the "e" spelling in general text.

Common Misconceptions About Gray and Grey

Common Myth	The Reality
Gray is the American spelling and grey is the British spelling.	Gray is the dominant American spelling, but grey is also used and accepted in American English, just less frequently.
Grey is the only correct spelling in the United Kingdom.	Grey is the standard British spelling, but gray appears in British English too, mainly in proper names and specific contexts.
Gray and grey are two completely different colors.	Gray and grey refer to the exact same color; the difference is purely a matter of spelling convention, not hue.
Using grey instead of gray is a grammatical error in America.	Using grey in America is not a grammatical error; it is a legitimate variant spelling recognized by American dictionaries.
Gray is the only spelling used for the color of a horse.	Gray is the standard spelling for horse coat color in America, but grey is used for horses in British and Australian contexts.
The spelling grey comes from a different color family than gray.	Gray and grey both derive from the same Old English word grǣg, so they share an identical color family and origin.
Gray is a newer spelling invented by Americans in the 20th century.	Gray was the common spelling in England before grey gained popularity, and gray has been used in America since colonial times.
Grey is always pronounced differently than gray.	Gray and grey are pronounced identically in standard English, both sounding like "gray" with a long a vowel.
You must use grey when writing about the color of storm clouds.	Storm clouds can be described with either gray or grey; the choice depends on your regional spelling preference, not the weather.
Gray is the only spelling accepted in scientific writing.	Scientific journals accept both gray and grey, but gray is preferred in American publications while grey is used in British journals.
Grey is the correct spelling for the color of a specific breed of dog.	Dog coat colors use gray in American breed standards and grey in British standards, but both refer to the same color.
Using gray in a British document will be marked as wrong by editors.	British editors accept gray as a variant, though they typically prefer grey for consistency in British English publications.
The word grey has a more elegant or sophisticated meaning than gray.	Gray and grey carry identical meanings and connotations; no evidence shows grey is more elegant in any English dialect.
Gray is only used for paint colors while grey is used for fabrics.	Paint and fabric industries use both gray and grey interchangeably, with brand-specific choices like Grey Goose or Gray Malin.
You should spell it gray when referring to hair and grey when referring to eyes.	Gray hair and grey eyes are both correct; the spelling choice follows regional convention, not the body part being described.
Grey is the original spelling used by Shakespeare and other old writers.	Shakespeare used gray more often than grey; gray was the dominant spelling in England until the 18th century.
Gray is a masculine spelling while grey is feminine.	Gray and grey have no gender associations in English; any perceived difference is purely subjective and not linguistically supported.
Mixing gray and grey in one document is always a spelling error.	Mixing gray and grey is inconsistent but not technically wrong; however, editors recommend choosing one spelling for the entire document.
Grey is used for the color of a specific type of granite.	Granite color names vary by supplier, with both gray granite and grey granite used commercially for the same stone.
Gray is the only spelling found in American dictionaries before 1900.	American dictionaries listed both gray and grey before 1900, with grey appearing in Noah Webster's early works as a variant.
You must use grey when writing about the Greyhound dog breed.	Greyhound is a proper noun with a fixed spelling, but the dog's coat color is described as gray or grey based on convention.
Gray is a color while grey is a shade of that color.	Gray and grey are the same color; neither is a shade of the other, and both can describe any lightness or darkness.
British people never use the spelling gray in any context.	British people use gray in proper names like Gray's Inn and in some technical fields, though grey remains the standard.
Americans never use the spelling grey in any context.	Americans use grey in proper names like Grey's Anatomy and in some brands, though gray is the standard choice.
Grey is the correct spelling for the color of a specific species of whale.	The gray whale is spelled gray in American English, but grey whale appears in British sources for the same species.
Using gray instead of grey will confuse British readers completely.	British readers understand gray perfectly; they may notice the spelling but will not be confused by its meaning.
Gray is a modern marketing invention used by paint companies.	Gray predates modern marketing by centuries, appearing in English texts from the 11th century, long before paint brands existed.
Grey is the only spelling used in the official names of British military units.	British military units use grey in names like the Grey Guards, but gray appears in some unit names and historical records.
Gray and grey have different meanings in color theory.	Color theory treats gray and grey as identical; both describe a neutral color between black and white with no hue.
You can never use gray and grey interchangeably in the same sentence.	Gray and grey are interchangeable in meaning, so using both in one sentence is understandable, though stylistically inconsistent.

Conclusion

Difference Between Gray and Grey is purely regional spelling, not meaning. Americans use gray with an "a"; British, Canadian, and Australian writers use grey with an "e". Pick gray for US audiences and grey for UK audiences, and stay consistent throughout your document.

FAQs on Difference Between Gray and Grey

What is the difference between gray and grey?: Gray and grey are two spellings of the same color, with gray being the standard American English spelling and grey the standard British English spelling, so the choice depends entirely on your audience's location.
Is gray or grey the correct spelling?: Both gray and grey are correct spellings, but gray is the preferred form in American English while grey dominates in British English, so neither version is grammatically wrong in any context.
Which spelling, gray or grey, is better to use?: The better spelling is gray for American readers and grey for British readers, so you should match your spelling to your primary audience's regional convention rather than choosing a universally superior option.
Does using gray or grey affect the cost of printing or design?: No, the spelling choice between gray and grey does not affect printing or design costs because both words represent the same color value and require identical ink or pigment amounts.
Are there any safety or risk issues with mixing gray and grey in writing?: Yes, mixing gray and grey in a single document creates a consistency risk that can distract readers and reduce your perceived professionalism, so you should pick one spelling and use it throughout.
How does gray versus grey compatibility work with style guides?: Gray is the required spelling in American style guides like APA and Chicago, while grey is required in British guides like Oxford, so your choice must align with the specific style manual you follow.
What is the most common beginner mistake with gray and grey?: The most common beginner mistake is using grey for American audiences or gray for British audiences, which immediately signals a lack of regional awareness and can undermine your writing's credibility.
Can gray and grey be used interchangeably without changing meaning?: Yes, gray and grey are fully interchangeable in meaning because they describe the identical color, so swapping one for the other never alters the substance of your message.
How do gray and grey apply to real-world use cases like paint or hair?: In real-world use cases, gray is the standard spelling on American paint cans and medical charts for hair color, while grey appears on British products, but both refer to the same visual shade.
Can I switch from using gray to grey in the middle of a project?: You can switch from gray to grey mid-project, but doing so creates avoidable inconsistency, so it is safer to finish with your original spelling unless you are revising the entire document for a new regional audience.