Hue Test

By Murat Şahin · Updated November 12, 2026 · How we test

How the hue test works

You see a grid of colored tiles. All of them are the same color except one, whose hue is turned slightly around the color wheel. Tap that tile. A correct answer takes you to the next level, where the difference is smaller and the grid may be bigger. A wrong answer costs one of your 3 lives, shows you the right tile, and gives you a new puzzle at the same level. When your lives run out, your score is the number of levels you cleared. Unlike the color blind test, which checks each cone type with number plates, this test measures how small a hue difference you can see.

The rules, exactly as the test uses them:

• Hue gap: 40° on level 1, then multiplied by 0.82 each level (about 18° on level 5, 10° on level 8, 4.5° on level 12, 2° on level 16). From level 18 it stays at the minimum of 1.5°.
• Grid: 2×2 on level 1, 3×3 on levels 2–4, 4×4 on levels 5–7, 5×5 on levels 8–10 and 6×6 from level 11.
• Colors: each puzzle picks a random hue and a random lightness. All tiles share the same lightness and chroma (colorfulness) in the OKLCH color space, so the odd tile is never simply lighter or darker. Only the hue angle differs.

OKLCH is the cylindrical form of OKLab, a color space Björn Ottosson introduced in a 2020 blog post. Equal steps in OKLab look roughly equally different to the eye across the color wheel, which keeps a 10° gap about as hard in blue as in orange. That makes it a fairer ruler than the plain HSL hue slider most color games use.

Reading your score

The result card shows the levels you cleared, the smallest hue gap you found and that gap as a color difference, ΔE in OKLab multiplied by 100. ΔE is the straight-line distance between the two colors in OKLab: the smaller it is, the closer the two colors are, whatever the hue.

The text under your score sorts the result into four plain bands:

• 16 levels or more: you found gaps of about 2° or less.
• 8–15 levels: you told apart gaps of 10° or less.
• 5–7 levels: you found gaps of 18° and smaller, but not yet 10° or less.
• Fewer than 5 levels: you only found large differences. Check the screen settings and play again; if small gaps stay invisible on several screens, try the color blind test.

There is no published average for this exact game, so the test does not compare you with other people. Compare yourself with yourself: your personal best and your last results are saved in this browser.

Why screens change the result

Hue discrimination depends on the display as much as on your eyes:

• Night mode, Night Shift, True Tone and blue-light filters tint the whole screen warm. Blues and purples lose contrast first.
• Brightness and glare. A dim screen or a reflection over the tiles flattens small differences.
• Viewing angle. On many laptop panels colors shift when you look from the side, so a tile at the edge can look different from one in the middle.
• Color profile and gamut. Wide-gamut phones and basic office monitors render the same numbers differently.
• 8-bit color. Most screens have 256 steps per channel. At the smallest gaps the two colors are only a few steps apart, so the screen, not your eye, sets the final limit.

For a fair comparison, play on the same device at the same brightness, in daylight or even room light.

What affects color discrimination

In the clinic, fine hue discrimination is measured with arrangement tests. The best known is the Farnsworth-Munsell 100 Hue test (Farnsworth, 1943), in which you put 85 colored caps in order of hue; the errors you make show how well, and along which color axis, you separate hues. Norms published by Kinnear and Sahraie (2002) show that hue discrimination improves through childhood, is best in young adulthood and slowly declines in later decades, partly because the lens of the eye yellows with age.

Other factors are temporary: tiredness, a long time in front of a screen, and adapting to colored light just before the test. Practice also helps. People who work with color, such as designers, printers or painters, often become better at judging small hue differences. For a color game that tests attention rather than eyesight, try the Stroop test.

Limits and when to see an eye doctor

This is a perception game on an uncalibrated screen. It does not diagnose color blindness or any eye condition. If you struggle with gaps that others find easy on the same screen, the color blind test checks red, green and blue cone vision directly, and the contrast sensitivity test checks how faint a difference in lightness you can see. See an eye doctor if colors start to look washed out, yellowish or different between your two eyes, or if color vision changes suddenly. These changes can come from cataract or other eye conditions that are worth checking early.

More checks like this are collected on our vision tests page.

Sources

• Ottosson, B. (2020). A perceptual color space for image processing [Blog post]. bottosson.github.io.
• Farnsworth, D. (1943). The Farnsworth-Munsell 100-hue and dichotomous tests for color vision. Journal of the Optical Society of America, 33(10), 568–578.
• Kinnear, P. R., & Sahraie, A. (2002). New Farnsworth-Munsell 100 hue test norms of normal observers for each year of age 5–22 and for age decades 30–70. British Journal of Ophthalmology, 86(12), 1408–1411.

Frequently asked questions