Gray card
A neutral grey reference card for setting exposure and colour balance in photography
A gray card is a flat, neutral-grey object used in photography and video to help set exposure and white balance. Its colour is chosen for a flat reflectance spectrum, meaning it reflects all visible light equally and appears as a true middle grey under any lighting. Gray cards are made from materials like paper or plastic and are a standard tool for consistent image results.
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- Reflects all visible light equally for true neutral grey
- Standard 18% reflectance for exposure reference
- Used for both exposure and white balance in photography
- Made from paper, plastic, foam, or fabric
- Kodak R-27 is a well-known gray card set
What colour is Gray card?
A gray card is a flat object coloured a neutral, middle grey. Its main feature is a flat reflectance spectrum, which means it reflects all colours of visible light equally. This makes it appear as a true grey under any light source, matching the colour of the light itself. The card is typically a medium shade of grey, often with 18% reflectance, and is used as a reference point for exposure and colour balance in photography and video. Unlike most objects, its colour does not shift with different lighting, making it a reliable tool for image makers.
Where does Gray card come from?
The gray card was developed as a practical tool for photographers and filmmakers who needed a consistent reference for exposure and colour. The Kodak R-27 set is a well-known example, providing both a grey and a white card for different reference needs. The idea is based on the need for a standard object that behaves predictably under varied lighting, which is achieved by ensuring the card's surface reflects light evenly across the visible spectrum.
How Gray card is defined
Gray cards are produced from materials such as paper, plastic, foam, or fabric. The key is to create a surface that reflects a fixed percentage of light (commonly 18%) and does so evenly for all visible wavelengths. This evenness is more precise than just appearing neutral to the eye. Some cards have a white reverse side with higher reflectance, up to 90%.
Where Gray card is used
Photographers, cinematographers, and video engineers use gray cards to measure exposure and set white balance. In practice, the card is placed near the subject, angled according to the main light source, and metered from a close distance. The reading helps adjust camera settings for accurate exposure. For digital cameras, a photo of the card can be used to set custom white balance, either in-camera or during editing. The card is also used for film photography to define the reference white under different lighting conditions.
Shades and relatives of Gray card
Gray cards are a specific shade of neutral grey, but other reference charts exist for broader colour calibration. These include colour charts with multiple patches for more complex adjustments. The gray card is mainly for neutral tones and exposure, while colour charts help with full colour rendering.
Colours that go with Gray card
Harmonies are worked out from the value #777777. Contrast ratios follow the WCAG 2 formula.
Questions people ask about Gray card
What colour is a gray card?
A gray card is a neutral, middle grey with a flat reflectance spectrum. It is designed to reflect all visible light equally, so it appears as a true grey under any lighting conditions.
What is a gray card used for?
It is used in photography and video to set correct exposure and white balance. By providing a standard reference, it helps ensure consistent and accurate colours in images.
Where does the name 'gray card' come from?
The name comes from its appearance and function: it is a card coloured grey, used as a reference for exposure and colour balance.
How is a gray card made?
Gray cards are made from materials like paper, plastic, foam, or fabric. The surface is designed to reflect a fixed percentage of light, usually 18%, evenly across all visible wavelengths.
How do you use a gray card for white balance?
You place the card in the scene, take a photo of it, and use that image to set the camera's custom white balance or adjust it during post-processing.
Good reading and sources
- Gray card on WikipediaEncyclopedia
- More pictures on Wikimedia CommonsPictures
- Wikidata recordOpen data
The facts on this page come from the Wikipedia article "Gray card", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). Rang rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.
It may contain mistakes. The swatch is an approximation: named colours are not fixed standards, and every screen shows them a little differently. If something is wrong, tell us. Last refreshed 2026-10-03.
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