Color Contrast Checker Tool is a small Android utility built for one job: telling you whether a text color actually reads against a background, using the same math the WCAG standard uses. We liked the idea enough to build our own browser version, Clarity Check, so anyone picking colors for a website, slide deck, or app doesn’t need to install anything to get the number. Pick two colors and the ratio updates the instant you change either one.
Check a contrast ratio now
It opens with a real pair already loaded, white text on Indigo, so you see a live ratio and pass/fail badges before you touch a thing. Drag either color picker or type a hex code to check your own pair.
How to use it
Set your text color under “Text” and your background under “On”, either by dragging the native color picker or typing a hex code directly. The ratio, the live text preview, and the three badges (AA text, AA large, AAA text) all update on every change, no button to press. Tap Swap to flip text and background, or tap one of the preset pairs to load a ready-made combination and see where it lands. Everything you type stays in your browser; your last pair is saved on your device so it’s still there next time you open the page.
How it compares to Color Contrast Checker Tool
Clarity Check keeps the part of the original app that actually matters day to day: type or pick two colors, get the WCAG contrast ratio and a clear pass or fail against the AA and AAA thresholds, instantly and without an account. The live text preview is our own addition, so you’re not just reading a number, you’re seeing the pairing render the way a reader actually would.
What we left out is the rest of a dedicated Android app: saved project history, batch-checking multiple pairs at once, and any offline access beyond a single browser tab. If you’re checking colors once while designing something on the web, Clarity Check is enough. If contrast checking is part of your regular workflow and you want it on your phone without a browser tab open, the Android app is the better fit.
One more thing worth mentioning: we held our own tool’s interface to the same standard it measures. Every piece of chrome text on the page, labels, badges, buttons, clears 4.5:1 contrast against its background. A contrast checker that couldn’t pass its own test would be a bad advertisement for the idea.
Get the full app
Color Contrast Checker Tool is a free Android app if you want contrast checking available outside the browser, with your history saved on the device.
Frequently asked questions
What formula does this contrast checker use?
The exact one from WCAG 2.1: relative luminance for each color from its sRGB channels, then the contrast ratio (L1 + 0.05) / (L2 + 0.05) using the lighter and darker luminance. It’s the same math browsers and design tools use, so a black-on-white pair reads 21:1 here just like it does anywhere else.
What do AA and AAA actually mean?
They’re WCAG 2.1 conformance levels for text contrast. AA requires at least 4.5:1 for normal text and 3:1 for large text (roughly 18px bold or 24px regular and up). AAA is stricter: 7:1 for normal text. Most sites and apps target AA; AAA is for content where legibility matters even more, like accessibility-focused products.
Is this the real Color Contrast Checker Tool?
No. Clarity Check is a browser tool we built, inspired by what the Android app does, and it is not affiliated with or endorsed by its developer. It runs the same WCAG formula, but it’s our own code and interface. The download links above go to the actual app.
Does it work offline, and is my data private?
Once the page loads, it makes no further network requests, so a dropped connection won’t stop it working. Nothing you type or pick is sent anywhere; your last colors are only saved in your own browser’s local storage.
Is it free?
Yes, completely. No ads, no account, no limit on how many pairs you check.
