# Never use color as the only signal

UI Tip #009 · UX & accessibility · 2026-10-12 · https://ui.praveenjuge.com/9/dont-rely-on-color

> About 1 in 12 men has some color blindness. Pair color with a second cue, like an icon, a label, a pattern or a position, so the state still reads in grayscale.

*Figure: A line chart whose two series gain a dashed line, shaped markers and direct labels, so colour is no longer the only way to tell them apart.*

## Why it matters

Color vision deficiency affects about 1 in 12 men and 1 in 200 women, and red and green are the colors most often confused. Color also disappears in grayscale printing, in bright sunlight, and on a screen with night mode on. When color is the only difference between two lines on a chart, or between a valid field and an invalid one, some people can't tell them apart at all.

## How to do it

- Pair every color with a second cue: a label, an icon, a pattern, a shape, or a position.
- On charts, name each series at the end of its line, and vary the line style and the marker shape, not only the hue.
- For states like errors and success, add an icon and words to the red or green.
- Underline links in body text, so they don't depend on being blue.
- Keep the colors themselves readable, too ([tip #004](https://ui.praveenjuge.com/4/text-contrast)).
- Test it: switch your screen to grayscale, or use the vision deficiency emulation in your browser's dev tools, and see what still reads.

## When it bends

Color can still lead. It's often the fastest cue for people who see it. It just can't be the only one.

## Sources

- [Use of Color, WCAG 2.2](https://www.w3.org/WAI/WCAG22/Understanding/use-of-color.html)
- [Colour blindness, Colour Blind Awareness](https://www.colourblindawareness.org/colour-blindness/)

---

From [UI Tips by Praveen Juge](https://ui.praveenjuge.com). Free to share, with a link back to https://ui.praveenjuge.com/9/dont-rely-on-color.