Color Contrast Checker

A color contrast checker measures the ratio between your text color and its background and tells you, in seconds, whether that pairing passes WCAG accessibility standards. Paste in two hex codes, pick a text size, and you get a precise ratio plus a pass or fail verdict for WCAG AA and AAA. If you publish web pages, landing pages, or Google Business Profile graphics, this is the fastest way to confirm your copy is actually readable before it ships.

This guide covers how the color contrast checker works, what the numbers mean, and why WCAG contrast ratio compliance is worth taking seriously even if you never think about accessibility law. It also walks through the anatomy of the results, the difference between AA and AAA, and how text size changes the math, so you can fix a failing color pair in under a minute instead of guessing at a new shade.

What is the Color Contrast Checker?

The color contrast checker is a free tool that calculates the contrast ratio between any two colors using the same relative luminance formula browsers and screen readers rely on. You enter a foreground hex code and a background hex code, choose whether the text is normal or large, and the tool returns a ratio such as 8.59:1 along with pass or fail badges for every WCAG AA AAA threshold. It is built for designers, marketers, developers, and local business owners who need an accessibility contrast checker that gives a real number instead of a guess.

Because the calculation uses the official WCAG relative luminance math, the result matches what a formal accessibility audit would produce. There is no eyeballing involved. You either clear the threshold for your text size or you do not, and the tool shows you exactly how far off you are.

How do you use the Color Contrast Checker?

Enter your foreground and background hex codes, pick a text size, and read the contrast ratio plus the WCAG AA and AAA pass or fail badges. The whole process takes under thirty seconds and runs entirely in your browser.

1. Enter your foreground (text) hex color, for example #13283d, in the first field. The live swatch updates as you type.
2. Enter your background hex color, for example #ffffff, in the second field so the preview shows the real pairing.
3. Choose the text size and weight, normal or large, bold or regular, so the tool applies the correct WCAG threshold.
4. Read the live sample text rendered in your exact colors to sanity check it with your own eyes.
5. Review the contrast ratio and the pass or fail badges for WCAG AA and AAA.
6. Click Copy result to grab the summary, or Download report to save a .txt file for your records.

The output is a single contrast ratio calculator number, such as 8.59:1, plus four verdicts covering AA normal, AA large, AAA normal, and AAA large text, so you know exactly which standards your color pair meets before you ship a page or an ad.

Why does WCAG contrast ratio matter for local SEO?

Good contrast keeps visitors reading instead of squinting and leaving, and that engagement is what actually moves local rankings, not the color choice itself. Bounce rate, dwell time, and scroll depth all respond to text readability contrast, and Google's local ranking signals respond to those behaviors.

Google does not score color directly, but it rewards the outcomes good contrast produces. When your text is easy to read, visitors stay on the page longer, scroll further, and convert more often. Those engagement signals, lower bounce rate and higher dwell time, feed into how Google evaluates page quality for local search results and the local pack.

Mobile matters even more here, since most local search traffic happens on a phone, often outdoors or in bright light. Someone searching for your business on the street needs strong contrast to read your hours, your address, or your call to action button. If they squint and bounce back to the search results, you lose a click that started on Google Maps.

There is a legal angle too. ADA-related web accessibility lawsuits have climbed for years, and low contrast text is one of the easiest and most common findings in an accessibility complaint. Running your site through a WCAG contrast checker before launch is cheap insurance against a demand letter, and it happens to overlap almost perfectly with good UX and SEO practice.

Contrast also sits next to the page experience metrics Google talks about publicly. Core Web Vitals measure loading speed and interaction responsiveness, not color, but the same visitors who bounce from a slow page also bounce from text they cannot read. Google's own Search Central documentation repeatedly ties good rankings back to a satisfying user experience, and a WCAG AA AAA contrast ratio checker is one of the fastest checks you can run to remove a real point of friction.

Understanding the contrast ratio output

Every result the tool returns breaks down into a handful of concepts. Knowing what each one means makes it much faster to fix a failing pair instead of randomly nudging a hex code until the badge turns green.

Contrast ratio

The contrast ratio compares the relative luminance of your two colors on a scale from 1:1, which is identical and invisible, up to 21:1, which is pure black text on a pure white background. The higher the number, the easier the pairing is to read. WCAG sets minimum thresholds based on text size and weight, not a single fixed number for every case.

WCAG AA vs AAA

AA is the practical standard most sites aim for: 4.5:1 for normal text and 3:1 for large text. AAA is stricter: 7:1 for normal text and 4.5:1 for large text. Most accessibility policies, and most legal settlements, reference AA as the bar to clear. AAA is worth reaching for critical content like calls to action, phone numbers, and legal disclosures. The W3C's own WCAG 2.1 contrast guidelines lay out the full reasoning behind both thresholds if you want the source document.

Large text vs normal text thresholds

Large text, roughly 18pt regular (about 24px) or 14pt bold (about 18.66px) and up, gets an easier WCAG contrast ratio requirement because bigger letters are inherently more legible at a lower ratio. A pairing that fails for body copy can pass for a heading using the exact same two colors, which is why the size selector in the tool changes your result.

Relative luminance

Behind every ratio is a relative luminance calculation, a weighted mix of the red, green, and blue channels that approximates how bright a color actually looks to the human eye. This is the same formula written into the WCAG 2.1 specification, which is why a color contrast checker built on it produces results that match a formal accessibility audit rather than a rough approximation.

Best practices and common mistakes

• Aim for WCAG AA at minimum on all body text. Treat AAA as the goal for important content like calls to action, phone numbers, and contact details.
• Do not rely on color alone to convey meaning. Pair a green pass state with text or an icon so colorblind users, roughly 1 in 12 men, still get the message.
• Test your real colors, not approximations. A close but slightly off hex code can flip a pass into a fail right at the 4.5:1 boundary.
• Remember that large text gets an easier threshold. Use the size selector instead of assuming one ratio applies to every element on the page.
• Check hover states, focus states, button text, and placeholder text, not just paragraphs. These are the spots most often missed in a manual accessibility contrast checker review.
• Avoid pure gray on white for fine print and disclaimers. Light grays frequently fail contrast ratio checks even when they look fine on a bright monitor.
• Re-check after a redesign. Brand refreshes swap accent colors often, and a new brand color used for body text can quietly break contrast that used to pass.
• Watch gradients and photo overlays closely. A contrast ratio calculator needs two flat colors, so test against the lightest and darkest points a gradient or background photo actually reaches, not just the average.

When should you run a color contrast checker?

Run it before you publish a new page, after any brand color change, and any time you overlay text on a photo. These are the moments low contrast most often slips through unnoticed.

Designing a local landing page: verify your headline, body copy, and button text all clear WCAG AA before you publish, so mobile searchers can read every word without zooming in.

Auditing an existing site: paste in the colors your CSS already uses to find low contrast spots that may be quietly raising your bounce rate and hurting text readability contrast across key pages.

Building a brand style guide: test every text and background combination your design system allows so designers never accidentally ship an unreadable pairing to production.

Fixing Google Business Profile assets and paid ads: confirm overlay text on photos and banners stays legible against busy backgrounds before customers ever see it in the local pack or on Maps.

Reviewing a developer handoff: before a new template goes live, run every text and background combination from the mockup through the checker so nothing ships with a color pair that only looked fine on one monitor.

Frequently asked questions

What contrast ratio does the color contrast checker require to pass?

For WCAG AA you need 4.5:1 for normal text and 3:1 for large text. For the stricter AAA level you need 7:1 for normal text and 4.5:1 for large text. The tool checks all four thresholds at once and shows a clear pass or fail badge for each.

Is this color contrast checker free to use?

Yes. The color contrast checker runs entirely in your browser at no cost, with no sign up, no API key, and no usage limits. Your colors never leave your device, so you can test as many pairings as you like while you design or audit pages.

What counts as large text under WCAG?

Large text is roughly 18pt (about 24px) and up for regular weight, or 14pt (about 18.66px) and up when bold. Large text qualifies for a lower contrast ratio threshold because bigger letters are easier to read, which is why the size selector changes your pass or fail result.

Does good color contrast actually help my SEO?

Not directly as a ranking factor, but it drives the signals Google does care about. Readable text keeps visitors engaged, lowers bounce rate, and improves time on page, and those user experience signals support local rankings, especially for mobile searchers arriving from Google Maps and the local pack.

Why does my color pair pass for headings but fail for body text?

Because WCAG applies a lower contrast ratio threshold to large text. A pairing that clears 3:1 for a big heading can fall short of the 4.5:1 needed for normal paragraphs. Always test body copy at its real size rather than assuming one heading result applies everywhere on the page.

Can I get sued for low contrast text on my website?

It is possible. ADA web accessibility lawsuits frequently cite insufficient color contrast as a specific finding, alongside missing alt text and unlabeled form fields. Running a WCAG contrast checker before launch is a fast, low cost way to close off one of the most common complaint categories.

Track where you actually rank

Readable pages keep visitors around, but you still need to know if you are showing up in local search once the page is live. ProMapRanker shows your true map rankings across a grid of locations, so you can connect on page fixes like contrast and readability to real visibility. Ready to see your local ranks? start free with 150 credits.

Related tools

Readability Score Checker grades how easy your copy is to read alongside your color contrast.

H1 / Heading Tag Checker audits your heading structure while you clean up on page accessibility.

Title Tag Length Checker checks that your page titles fit before they get cut off in search results.

Meta Description Length Checker keeps your meta descriptions inside the safe character limit.

Word Counter tracks the length of your page copy as you write it.