Interval Timer

The Interval Timer cycles through Prepare → Work → Rest for a set number of rounds. It's ideal for HIIT (High-Intensity Interval Training) or Tabata style routines that alternate short bursts of intense work with rest.

Enter the prepare, work, and rest durations (seconds) and the number of sets, then press Start. A prepare phase runs first, followed by work and rest repeated for the configured sets. Use Pause to hold and Start again to resume; Skip ends the current phase immediately and moves to the next; Reset restores the initial configuration.

Use it for Tabata (20s work / 10s rest x 8 rounds), circuit training, home workouts, strength or cardio intervals, or any Pomodoro-style routine that alternates focused work and rest.

Interval training alternates high-intensity work with recovery rest. The work-to-rest ratio (2:1, 1:1, 1:2, etc.) shapes how demanding a session feels, and people commonly adjust the rest portion to their fitness level. Since exact intensity and ratios depend heavily on individual health, this page offers no medical advice on specific workouts — it's a guide to the timer feature itself.

Tabata is commonly described as "a 4-minute workout," from 20s work + 10s rest × 8 rounds = 8×30s = 240s (4 minutes). Checking this timer's actual code, though, it's built to skip the rest after the final set. So with 20s work, 10s rest, and 8 sets, the real total is 20×8 (work) + 10×7 (rest, excluding the last set) = 160+70 = 230 seconds (3 min 50 sec) — 10 seconds shorter than the commonly cited 4 minutes. With prepare set to 0, that 3:50 is the full routine length.

This timer lets you freely set prepare, work, and rest durations (in seconds) and the number of sets, and your last-used settings are saved in the browser and restored on your next visit. It also supports pause/resume and skipping the current phase, with a sound and color change marking every transition.