Chart Color Contrast Checker
Last reviewed on 2026-05-22.
Verify that adjacent slices, labels, and backgrounds meet accessibility standards
Why contrast matters in charts
When two adjacent pie slices have similar luminance, viewers with low vision or color blindness can't tell where one ends and the next begins. A clear visual boundary requires at least a 3:1 contrast ratio between adjacent colors — the same threshold WCAG uses for non-text UI elements.
What the grades mean
- 3:1 — minimum for adjacent chart elements and large text.
- 4.5:1 — WCAG AA for normal-sized text (chart labels, captions).
- 7:1 — WCAG AAA for normal text, the strict accessibility level.
How to fix low-contrast pairs
- Vary lightness as well as hue. Two mid-tone colors (e.g., medium blue + medium green) almost always fail; pair a dark with a light instead.
- Don't put a yellow slice next to a light-orange slice. They share luminance and read as one slice.
- Add a 2-pixel white or background-colored border between slices. It's a tiny visual tweak that dramatically improves slice separation.
- Test the whole palette against itself in pairs — adjacency is what matters, not individual colors.
Tip: For colorblind-safe palettes, use ColorBrewer's 'qualitative' sets — they're tested across multiple types of color vision deficiency and work out of the box for charts.
Contrast ratio: —
Frequently Asked Questions
What contrast ratio do chart slices need?
At least 3:1 between any two adjacent slices. For text labels on slices, 4.5:1 against the slice background (WCAG AA).
Is contrast the same as colorblind safety?
Related but not identical. High contrast helps colorblind viewers, but the surest defense is using palettes designed and tested for color vision deficiencies — ColorBrewer's qualitative sets are a good starting point.
Why does this tool only compare two colors?
Most contrast issues in charts come from adjacent slice pairs. Check the riskiest pairs in your palette one at a time — usually that's neighbors with similar lightness.