What is the best subtitle contrast checker?

The best checker uses the published WCAG contrast formula and handles the transparent-background case honestly. This free tool computes the exact WCAG 2.x ratio for your color pair and, for transparent captions, reports a worst-case advisory estimate instead of pretending it can guarantee readability over video.

Is there a free subtitle contrast checker?

Yes — this subtitle contrast checker is completely free with no signup. Enter your text color, background color (or "none" for transparent), and font size to get the ratio, the AA/AAA verdict, and fix suggestions.

How to check subtitle contrast?

Type your caption text color and background color as hex values, add the font size, and run the check. Aim for at least 4.5:1 (or 3:1 for large bold captions) — the tool tells you exactly where your pair lands and how to fix it.

How does a subtitle contrast checker work?

This one applies the WCAG relative-luminance formula to the two colors you enter and compares the result to the AA/AAA bars for your text size. It checks color pairs only — it cannot see your video, so for transparent backgrounds it reports a worst-case estimate against black and white frames and labels it advisory.

What is a subtitle contrast checker?

A subtitle contrast checker is a free online tool that gives you quick, accurate results without spreadsheets or manual math. This version runs entirely in your browser for instant, private results.

What is a good subtitle contrast checker score?

Aim for the top rating band shown in the results. If your score is low, the tool highlights exactly what to fix — usually small changes make a big difference.

How do I check subtitle contrast checker?

Paste or enter your content above and the checker analyzes it instantly. Review the results and apply the suggested fixes.

Subtitle Contrast Checker

What is Subtitle contrast checker?

Caption Contrast Checker — Check with this free subtitle contrast checker — enter text and background colors for a WCAG ratio, AA/AAA verdict, and fix tips. Test your colors now.

The tool computes the WCAG 2.x contrast ratio: relative luminance L = 0.2126R + 0.7152G + 0.0722B (sRGB-linearized), ratio = (Llighter + 0.05) / (Ldarker + 0.05). Text counts as "large" at 24px or more, or 19px+ when bold. The verdict bars are AA 4.5:1 (3:1 for large text) and AAA 7:1 (4.5:1 for large text). If the background is "none" (transparent over video), no ratio can be guaranteed — the tool reports the worse of the ratios against pure black and pure white frames as a worst-case advisory estimate. This checks color pairs you type; it does not sample video frames.

Why use this subtitle contrast checker?

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Built for subtitle contrast checker

Check with this free subtitle contrast checker — enter text and background colors for a WCAG ratio, AA/AAA verdict, and fix tips. Test your colors now.

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Transparent & honest

Checks text/background color pairs you provide — it does NOT sample video frames and cannot measure your rendered captions.

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Private by design

Everything runs in your browser. Your inputs never leave your device.

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Works everywhere

Fully responsive — perfect on desktop, tablet, and mobile. No app needed.

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Regularly updated

Regularly maintained and reviewed to ensure accuracy.

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Free forever

No accounts, no limits, no watermarks. Use Caption Contrast Checker as much as you need.

How to use Caption Contrast Checker

1Enter your caption text color as a hex value, e.g. #FFFFFF.
2Enter the background color as hex, or type "none" if your captions sit directly on video with a transparent background.
3Optionally add a stroke color — the tool checks text-vs-stroke and stroke-vs-background separately.
4Enter the caption font size in pixels and tick "bold" if the text is bold.
5Read the contrast ratio, the WCAG verdict (fail, AA, or AAA), and the suggestions for fixing weak pairs.

What can you do with Caption Contrast Checker?

Caption text readability checker — Check with this free subtitle contrast checker — enter text and background colors for a WCAG ratio, AA/AAA verdict, and fix tips.
Subtitle color contrast test — Check with this free subtitle contrast checker — enter text and background colors for a WCAG ratio, AA/AAA verdict, and fix tips.
Wcag caption contrast — Check with this free subtitle contrast checker — enter text and background colors for a WCAG ratio, AA/AAA verdict, and fix tips.

Good to know

Checks text/background color pairs you provide — it does NOT sample video frames and cannot measure your rendered captions.
A "none" (transparent) background has no single contrast ratio; the reported number is a worst-case advisory estimate, not a guarantee.
Ratios are WCAG 2.x math estimates on the colors typed; always preview captions on real footage.

How it works

The tool computes the WCAG 2.x contrast ratio: relative luminance L = 0.2126R + 0.7152G + 0.0722B (sRGB-linearized), ratio = (Llighter + 0.05) / (Ldarker + 0.05). Text counts as "large" at 24px or more, or 19px+ when bold. The verdict bars are AA 4.5:1 (3:1 for large text) and AAA 7:1 (4.5:1 for large text). If the background is "none" (transparent over video), no ratio can be guaranteed — the tool reports the worse of the ratios against pure black and pure white frames as a worst-case advisory estimate. This checks color pairs you type; it does not sample video frames.

Examples

Classic white on black

Maximum 21:1 ratio — comfortably AAA for any text size.

Transparent captions with stroke

Worst-case advisory ratio plus a separate stroke check, since the background is moving video.

People also search for these — this tool handles them all:

subtitle contrast checkercaption text readability checkersubtitle color contrast testwcag caption contrast

Frequently asked questions

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