What counts as large text under WCAG 2.1?

Roughly 24px for normal weight text, or about 18.66px when bold. Those correspond to 18pt and 14pt in the point sizes the specification uses, and they are the boundary below which the 4.5 to 1 requirement applies instead.

Is 3 to 1 safe for body copy if the text is simply big?

Only while it stays above the large-text size. The ratio belongs to the pair, so the same colors that pass for a 32px heading would fail the normal-text requirement if the type were reduced later. Check the size your design will actually ship with.

Why does AAA use a different number for large text?

AAA sets 4.5 to 1 for large text and 7 to 1 for normal text. This page applies the AA large-text figure of 3 to 1, so a pair can pass here and still fall short of the enhanced level for the same size.

Does bold text get a lower requirement than regular text?

It gets one at a smaller size. Bold text becomes large at roughly 18.66px rather than 24px, so heavier type reaches the relaxed threshold sooner. Below that size the same 4.5 to 1 applies as for regular text.

Can I use a 3 to 1 pair for a button label?

Only if the label is set large and the button's own boundary also meets the non-text requirement. A button label at ordinary size still needs 4.5 to 1, and the fill against its surrounding surface is a separate 3 to 1 check.

Large Text Contrast Checker

Foreground

Background

Large text AA

14.68:1

Pass (≥ 3:1)

Sample text here

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UI Component Contrast Checker

Non-text contrast for UI elements (3:1)

Large Text Contrast Checker tests a pair against the 3 to 1 minimum that WCAG 2.1 AA allows for large text, the relaxed bar that applies to headings and display type.

What is Large Text Contrast Checker?

Large Text Contrast Checker tests a color pair against 3 to 1, the lower contrast minimum that WCAG 2.1 AA permits for large text. It is the check to use for headings, display type and oversized labels, where the stricter 4.5 to 1 requirement does not apply and checking against it would reject pairings that are perfectly acceptable.

The relaxation exists because size compensates for a certain amount of lost contrast, and it applies at two points on the type scale:

Large text at 3 to 1, where large means approximately 24px, or 18.66px when the text is bold.
Ordinary text at 4.5 to 1, which is the bar this page deliberately does not apply.
AAA large text at 4.5 to 1, one step above this page's gate, for comparison.

This page is aimed at the first of those. Every pair you enter is compared against 3 to 1 and reported as Pass or Fail with the threshold shown beside the verdict.

The figure being compared is the WCAG 2.x contrast ratio. Both colors are parsed and converted to sRGB, each channel is linearised out of its gamma curve, and the linear values are weighted 0.2126 red, 0.7152 green and 0.0722 blue to produce a relative luminance. The ratio is the lighter luminance plus 0.05 divided by the darker plus 0.05, rounded to two decimals before comparison. Because 3 to 1 is a low bar by ratio standards, a wide range of mid-tone pairs clear it, which is exactly why the large-text exemption is only safe for type that genuinely is large.

Think of the result as the large text AA contrast verdict for a heading contrast pairing, with the 3 to 1 contrast bar as the only threshold tested. The allowance is generous, so most sensible foreground and background pairs clear it, and the more useful question is usually how far above the bar you sit rather than whether you passed at all. A pair that also clears 4.5 to 1 removes the need to police the size boundary entirely, which is worth the extra effort on any heading that might later be reused at a smaller size.

That last point is the main limitation, and a few others follow from it.

The tool does not know how large your text is. It applies the large-text threshold to whatever pair you enter, so using it on body copy would return a pass that the specification does not grant.
There is no size or weight input, so the boundary between large and ordinary text is yours to police.
AAA is not assessed. A pair can pass here and be nowhere near the 7 to 1 enhanced level.
Non-text contrast is out of scope, including borders and focus rings, which carry their own requirement.
Two colors only, with no alpha and no surface behind them.

Use this page for headings, hero text, chart labels set large and any other type that is comfortably above the large-text size. For running copy, use the ordinary AA check instead, and for a boundary rather than text, use the component or focus check. When in doubt about whether your text counts as large, check both: a heading pair that also clears 4.5 to 1 is immune to the question entirely.

How to use Large Text Contrast Checker

Set the heading or display color in the foreground field.
Set the surface behind it in the background field.
Read the ratio in the panel heading, to two decimal places.
Check the Pass or Fail verdict against the 3 to 1 threshold, and confirm your text really is large before relying on it.

When to use Large Text Contrast Checker vs related tools

Use the large text contrast checker for headings, display type and any label set comfortably above the large-text size, where the 3 to 1 allowance is the correct bar. Use the WCAG 2.1 AA checker for running body copy, the contrast checker when you want the large-text and normal-text thresholds side by side for the same pair, and the UI component contrast checker or focus indicator contrast checker when the thing being judged is a boundary rather than type.

Privacy & Security

This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.