Usable by everyone

Contrast checker

Text that is hard to read shuts people out. Drop in a text colour and a background, and see straight away whether the combination holds up.

Start from

Text colour Background

— Contrast ratio

A heading at 24px

Body text at 16px. This is the size most of your interface is written in, so it is the one that matters most.

A button A caption, often the first thing to fail.

is the level most projects should meet. Large text is 18.66px bold or 24px and up.

Good to know

How to read the result

What the levels mean

AA is the level most projects should meet: a ratio of at least 4.5:1 for normal text. AAA is stricter at 7:1 and is worth aiming for on long reading text.
What counts as large text

Large text is 18.66px and bold, or 24px and up. It gets a lower bar because size already helps legibility.
Contrast is not the whole story

Passing the ratio does not make an interface accessible on its own. Never carry meaning with colour alone, and check both your light and dark themes.

More tools

These are the small ones. The bigger ones we develop for the people who ask.