March 10, 2026
Is your monitor gaslighting you?
Show HN: What's my JND? – a colour guessing game
Viral color test has HN blaming their screens and flexing tiny numbers
TLDR: A viral web game shows two colors to find your “just noticeable difference,” the smallest change your eyes can detect. The community’s hooked, split between bragging rights and blaming screen calibration, while others praise a linked explainer—turning a fun clicker into a showdown of human vision vs hardware.
Two colors. One click. Infinite bragging rights. The HN crowd dove into “What’s my JND?”—a simple game that finds your Just Noticeable Difference (the tiniest color change your eyes can spot)—and immediately split into camps: the tiny number flexers chasing 0.0030 and the realists seeing the dev’s “most people around 0.02.” Cue competitive chaos.
The hottest drama? Is it your eyes… or your monitor. One player couldn’t break 0.0030 and wondered if screen quality is sabotaging scores; another got stuck at 0.0050 and just yelled “I blame my screen!”—fast becoming the thread’s catchphrase. Meanwhile, the nerds-with-hearts praised the companion deep-dive: “The associated deep-dive article is great,” one wrote, while another cheered how it turns “decimal places in CSS colors” into something you can actually use. If you’re new here, a helpful commenter spelled it out: JND means the smallest color change you can actually see.
Between addictive attempts, monitor self-doubt, and mini-lectures on human perception, the vibe is part game night, part science class, part group therapy. People are linking the deep dive, comparing thresholds like high scores, and arguing whether calibration is king or eyes don’t lie. Either way, nobody’s closing that tab anytime soon.
Key Points
- •The game shows two colors and asks users to click on the line between them.
- •Difficulty increases as the colors move closer together each round.
- •The objective is to find the user’s Just Noticeable Difference (JND) in color perception.
- •The process generally takes about 40 rounds to estimate the JND.
- •Most users achieve a JND around 0.02, with individual variation expected.