Reaction time training, measured to the millisecond.
Wait for the flash, react, and see exactly how fast you are. Keep your scores, climb the leaderboard and duel friends live when you sign in.
One account across web, iOS and Android.
How the reaction time test works
Three steps, one to ten reps. Most runs take under a minute.
Wait for it
The screen stays dark for a random beat. React early and it's a false start.
React on yellow
Tap, click or press space the instant the screen flashes yellow.
See your time
Every rep is timed from the frame the flash was painted, then graded.
How fast is fast?
Times are graded the same way on every platform.
- Eliteunder 200 ms
- Fast200–279 ms
- Average280–379 ms
- Slow380+ ms
Sign in to go further
Training is free without an account. Signing in adds the parts that keep you coming back.
Keep every run
Your history and personal bests, so you can watch your average come down week by week.
Climb the leaderboard
Boards for every difficulty and rep count, this week and all-time.
Duel your friends
Add friends, challenge them to live 1v1 rounds and settle it head-to-head.
Duel anyone, on any device.
Duels run in real time between web, iOS and Android. The same stimulus fires for both players at the same moment, wherever they are.
Matches with a web player use tap mode, since a browser can't read a punch.
Train with a real punch
The iOS and Android apps add combat sports mode: your phone's accelerometer detects the strike, and on iOS an Apple Watch can measure it from your wrist.
