Everything About the Interval Timer
An interval timer is built for workouts that alternate fixed work and rest periods. For high-intensity interval training (HIIT), Tabata, circuit training, and home workouts where you need to nail "20 seconds hard, 10 seconds rest," all you need is your phone. You can fine-tune prep time, work time, rest time, number of sets, number of rounds, and rest between rounds — so beginners and advanced athletes alike can build their own routine.
The most popular Tabata protocol repeats 20 seconds of work + 10 seconds of rest for 8 sets, totaling 4 minutes. Tap the "Tabata" preset to apply it instantly, or use the "HIIT" preset for a longer high-intensity session of 40s work + 20s rest for 10 sets. Add multiple rounds to repeat the full block, with an optional rest between rounds — ideal for circuit-style training.
During a workout, oversized numbers fill the screen with color-coded phases (prep = yellow, work = green, rest = blue) so you can read the remaining time from across the room. A beep sounds on every phase change and on the final 3-second countdown, so you can prepare for the next move without watching the screen — and you can mute it anytime if the sound gets in the way. A Wake Lock keeps the screen on while you train, and it works fine on devices that do not support it.
Instead of accumulating setInterval drift, this timer calculates the remaining time from the real elapsed clock (Date.now), so the timing stays accurate even if you switch tabs or the screen sleeps. Your settings are saved in the URL — share the link to hand a friend or a member the exact same workout setup — and you can store your favorite configuration in the browser to load it again next time.