Huekle
Guess today's color in 5 tries.
Warm or cool? See the theory →
About Huekle — read a color and close the gap
Huekle trains the most fundamental color skill of all: holding a target shade in your mind and judging how far your guess sits from it along three axes at once — hue, lightness and saturation. That three-way estimate is exactly what you do when matching a paint chip to a wall, picking the swatch that reads true under shop lighting, or deciding whether a photo needs to go warmer or cooler.
You have five tries to land on the day's hidden color. After each guess, Huekle tells you whether you are too warm or cool, too light or dark, and too vivid or muted, so every attempt narrows the gap and teaches you to read those directions faster.
The feedback maps onto how we describe color in three dimensions. Learn warm and cool color temperature, or explore the full set of Learn about color guides.
What Huekle trains
Huekle works your three-axis color matching: holding a target shade in mind and judging how far your guess sits from it along hue, saturation and lightness at once. The day's color is hidden. You set three sliders, lock in a guess, and the game tells you only which way to move on each axis, never how far. Five tries, and everyone plays the same target that day. The hard part is that the axes interact: a swatch can read as "too dark" when what you actually overshot was saturation.
How to play
Move the Hue, Saturation and Lightness sliders until the large swatch looks like your best guess, then press Lock in guess. Three hints appear. Hue shows a tick when you are within eight degrees, otherwise an arrow for which way to turn the slider plus the word warmer or cooler. Saturation and lightness show a tick within five points, otherwise "more" or "less". Every locked guess joins a history strip with its own swatch and closeness score, and the bar beside it turns green from 90% up, so you can see whether you are converging or wandering. The hue slider wraps at the 0°/360° seam, so an arrow never sends you the long way round; arrow keys step one degree, Shift steps ten.
How scoring works
Each guess gets a closeness percentage. Huekle converts your guess and the hidden target into CIE L*a*b*, measures the straight-line distance between them (a Delta-E), and turns that into a score out of 100, so the number follows perceived difference rather than slider positions. Your result for the day is your best guess, not your last. The round ends early if you reach 98%, or if all three hints turn to a tick at once, meaning hue within eight degrees and saturation and lightness each within five points. Otherwise you play out all five tries and keep the best.
What your score means
Read the result as a rough band rather than a precise verdict:
| Outcome | Rough interpretation |
|---|---|
| Solved (98%+, or all three ticks) | You read all three directions and converged |
| Best 90-97%, the history strip's green band | Close; usually one axis was still drifting |
| Best below 90% | Room to improve, often by fixing hue first |
One day is noisy. The trend across many days is the honest signal, and how many tries you needed matters as much as the percentage.
Common mistakes
The most common error is chasing all three sliders at once. Fix hue first, because a wrong hue makes every judgement about the other two unreliable, then settle lightness, then saturation. The second trap is over-correcting: reading "more" and doubling the value instead of halving the remaining gap. Third, players follow the word and ignore the arrow; "warmer" describes the target's temperature, while the arrow is the movement instruction for the wrapping slider. Finally, an uncalibrated display or a night-shift filter changes how the same values look.
Practice progression
(5 min, beginner) Play the daily target and spend the first two tries on hue alone, accepting that the other axes will be wrong. (10 min, intermediate) In the practice tab, set the color range to pastel or to one temperature family, where the axes are harder to separate, and try to halve the gap every try. (weekly) Alternate with Huemory for memory and Hueddle for fine discrimination, and read one guide, starting with hue, saturation and lightness.
The science behind it
Your ability to tell two colors apart is not uniform across color space: classic work on color-matching sensitivity showed that the smallest detectable difference depends on where in the space you are, which is why Huekle scores in a perceptual space rather than in slider units. The warm-cool judgement leans on opponent coding, the reason temperature feels like one continuum rather than an arbitrary axis. Background: how the eye sees color and color difference and Delta-E.
Limitations
Huekle is a game and an informal self-check, not a clinical or diagnostic tool. Rendering, calibration, ambient light and your chosen theme all affect what you see, so results from different devices are not comparable and a single day tells you little. If you suspect a color vision difference, a proper test is the right route; see color vision differences.
Where it shows up
Three-axis matching is the everyday version of a professional skill. Someone holding a paint chip against a wall is doing exactly this: deciding whether the sample is the same hue but slightly lighter, or the right lightness but too muted. A photographer looking at a portrait decides whether the skin reads too warm, too dark or too saturated, and those are three separate corrections that a beginner collapses into "it looks off". A decorator matching a replacement tile, someone buying thread for a garment brought from home, a printer approving a proof against a brand swatch: all are estimating the same three directions and then moving in one of them. The habit that transfers is naming the difference before acting on it. Instead of "not quite right", you learn to say "same hue, one step too light, a touch too vivid". That is a description someone else can act on, and one you can act on yourself in front of a shelf. Huekle will not calibrate your monitor or make you a colorist; it makes the three axes feel like separate dials rather than one vague impression, and that separation is what makes color decisions repeatable.
Ready to find today's color? One hidden shade, five tries, about a minute, and a new target tomorrow.
Frequently asked questions
How many tries do I get?
Five. The round can also end sooner: reaching 98% closeness, or a tick on all three hints at once, finishes it immediately.
What does the closeness percentage measure?
The distance between your guess and the target in CIE L*a*b*, a space built so that equal distances look like roughly equal differences. It is not a distance between slider numbers.
Why does the hue hint show an arrow and a word?
The arrow says which way to turn the wrapping hue slider by the shorter route; the word says whether the target is warmer or cooler than your guess.
Does everyone get the same color?
Yes. The target comes from the day's puzzle number, so every player sees the same one, and it changes at midnight local time.
Can I practise without waiting for tomorrow?
Yes. The practice tab lets you set difficulty, the number of tries and a color range such as warm, cool or pastel. Practice rounds do not affect your daily streak.
Related reading & games
- Hue, saturation and lightness: the three axes, explained properly.
- Warm and cool color temperature: what the hint really means.
- Huetween (find the midpoint color) and Huefork (judge how much lighter or darker): related estimation games.
- All Learn about color guides.
Source: MacAdam, D. L. (1942), Visual sensitivities to color differences in daylight, Journal of the Optical Society of America 32(5), 247-274.
Understand it, now train it. The daily games stay free forever. A Personal Pass adds progress tracking (trends + export); Teacher / School tools let you assign it and follow a whole class. For teachers & self-learners →