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Color Contrast Checker

WCAG contrast ratio between text and background, with AA/AAA pass-fail and a live preview.

Related tools

All Colours & CSS tools →
Color InverterInvert a colour (255 − RGB) or take its complement, in HEX/RGB/HSL/CMYK with the contrast between them.Color Scheme GeneratorDerive complementary, analogous, triadic, tetradic, split and monochromatic schemes from a base colour.Image Color PickerLoad an image, click to sample any pixel and extract a dominant palette, with HEX and RGB for each swatch.Random Color Palette GeneratorBuild a harmony-based palette you can lock and regenerate, Coolors-style, with copy-all HEX.Color converterConvert a colour to HEX, RGB, HSL, HSV, CMYK, LAB and OKLCH, with contrast.CSS CompressorMinify CSS by stripping comments and whitespace to shrink your stylesheet's size.CSS Flexbox PlaygroundExperiment with flex-direction, wrap, justify-content, align-items and gap — live preview and copyable CSS.CSS Grid GeneratorBuild a CSS grid layout visually — columns, rows, gaps and alignment — with a live preview and copyable CSS.

Open Color Contrast Checker and you get an answer straight away, with no account to create. It sits under Colours & CSS in our catalogue, alongside Color Inverter and Color Scheme Generator.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What is Color Contrast Checker?

WCAG contrast ratio between text and background, with AA/AAA pass-fail and a live preview.

When would I actually use this?

Moving a colour between a design tool and a stylesheet, building a palette around one brand colour, and checking text will be readable on it.

What is the most common mistake?

Judging contrast by eye. Two colours that look distinct on a bright monitor can fail the accessibility ratio outright, and the ratio is the thing an audit will measure.

How is Color Contrast Checker different from Color Inverter?

They sit next to each other but answer different questions: Color Inverter is the one to open when you need it to invert a colour (255 − RGB) or take its complement, in HEX/RGB/HSL/CMYK with the contrast between them. Pick whichever matches what you're starting from — both are free.

Is there a tool for the next step?

Color Scheme Generator is the closest one after this: Derive complementary, analogous, triadic, tetradic, split and monochromatic schemes from a base colour.

What else is worth having open alongside it?

Image Color Picker and Random Color Palette Generator — they come up in the same task often enough to be worth a second tab.

Where do the figures come from?

Conversions between HEX, RGB and HSL are exact. Contrast follows the WCAG 2 relative-luminance formula; CMYK is device-dependent, so a screen value is an approximation of what will print.

Further reading

All guides →
ExplainerContrast Ratio: How WCAG Actually Computes ItThe WCAG ratio is (L1 + 0.05) ÷ (L2 + 0.05), and L is relative luminance, not brightness. Green carries 71.52% of it and blue 7.22%, which is why pure blue on white passes at 8.59:1 while mid grey fails at 3.95:1. Here is the whole computation, run end to end.ExplainerGradients, Banding, and Why the Middle Looks MuddyInterpolating in sRGB averages gamma-encoded numbers, so the midpoint of red to green is #808000 when the half-light answer is #bcbc00 — 57.2% too little light. Banding is a separate arithmetic problem: 8 bits give 256 steps, and a dark gradient may have only 28 of them. Here is both, computed.ExplainerColour Schemes Are Geometry on a Wheel — and the Wheel Is WrongComplementary, triadic, analogous and split-complementary are just rotations: add 180°, 120°, 30° or 150° to a hue. The arithmetic is trivial. The problem is that the HSL hue circle is not perceptually uniform — yellow and blue at the same HSL lightness differ in luminance by 12.85 times — so a generated palette has to be contrast-checked afterwards.How-toHEX vs RGB: How to Read and Convert ColoursHEX and RGB are two notations for the same colours. Here's how to read each, convert between them, and add transparency.GuideWhat a Minifier Can Remove, and What It Must NotMinification has to preserve meaning, and the interesting part is the whitespace that carries meaning: the descendant combinator, the spaces inside calc(), the gap between two inline elements. Measured here on real files, including how much brotli was going to save you anyway.GuideBeautify or Minify: What Each Is For, and What It Does to the WeightFour real stylesheets run through the minifier, measured raw and after gzip. Stripping every space saved 48, 103, 104 and 147 compressed bytes; stripping comments saved 57, 1 358, 2 420 and 1 042. Plus the five inputs this minifier breaks.