Sub250: Reaction Time Test

Sub250 shows your device's latency floor next to every score. See what's reflex, what's hardware. Five modes. Median of ten. Free.

Five reaction-time modes with native iOS timing. Your device's latency floor shows next to every score in ms. What's reflex, what's hardware. Free.

Sub250 measures your reflexes the way they should be measured. The headline number is the median of your last ten attempts, not your luckiest tap, with millisecond-level precision and your device's calibrated latency floor shown alongside every score.

FIVE REACTION-TIME MODES • Simple RT: wait for green, tap as fast as you can. • F1 Lights Out: five red lights, then go, exactly like the grid. • Go / No-Go: tap green, hold red. The clock catches you if you flinch. • Choice RT: four zones, react to whichever lights up. • Target Hunt: tap pop-up targets in random spots before they fade. Sixty seconds.

WHY SUB250 IS DIFFERENT

Latency-honest. Every device adds touch-to-display latency. Sub250 calibrates yours in about three seconds at startup and shows the floor in milliseconds next to every score. We think every reaction-test app should.

Median-of-10. The score reflects skill, not variance. Best-of-N is available as a secondary number, never the headline.

Anti-anticipation. Randomized stimulus intervals on every interval-based mode. Jumpstarts cost a re-arm. The clock is honest.

100% free. No accounts. No servers. No subscriptions. No ads. No in-app purchases. Ever.

Local-only. Your sessions never leave your device. There is no leaderboard to game, no profile to fill out, no email to give up.

BUILT FOR COMPETITIVE GAMERS

If you play Counter-Strike, Valorant, Apex, racing sims, or anything else where the difference between 200 and 230 ms matters, Sub250 was built for you. The score is the score.

Open Sub250, run the calibration, and see what your real reflex looks like.