A HIIT (high-intensity interval training) timer with configurable work, rest, warm-up, and cool-down phases. Set up your intervals, press start, and the timer cycles through the phases with audio cues at each transition.
How it works
The timer sequences through phases in a fixed order:
Each work/rest pair is one round, and the number of rounds is configurable. Any phase with a duration of 0 is skipped — set warm-up to 0 to jump straight into the first work round, set cool-down to 0 to end after the last rest, set rest to 0 for a continuous workout.
The current phase, remaining seconds in that phase, and total elapsed/total duration all update every second while the timer runs. When a new phase begins, the timer plays a short beep. Pausing freezes the clock; resuming picks up at the exact second you paused. Reset clears everything back to the initial state.
Example: Tabata protocol
The classic Tabata protocol is 8 rounds of 20 seconds work + 10 seconds rest, total 4 minutes. Set the tool to:
- Rounds: 8
- Work: 20
- Rest: 10
- Warm-up: 0 (or 30 seconds for a warm-up)
- Cool-down: 0
Press start. The timer counts down 20 seconds of work, beeps, 10 seconds of rest, beeps, and so on for 8 rounds. Total workout is 4 minutes if no warm-up or cool-down, 4:30 with a 30-second warm-up.
Example: strength interval training
For a 10-round strength-focused interval with longer rests:
- Rounds: 10
- Work: 40
- Rest: 20
- Warm-up: 60
- Cool-down: 30
Total workout is 1:00 + 10 × (0:40 + 0:20) + 0:30 = 11 minutes 30 seconds. Good for kettlebell, dumbbell, or bodyweight circuits where you need enough rest to maintain form under load.
Example: running intervals
6 × 400m intervals with 90-second walking recovery:
- Rounds: 6
- Work: 90 (or whatever your expected 400m time is)
- Rest: 90
- Warm-up: 300 (5 minutes)
- Cool-down: 300 (5 minutes)
Total is 5:00 + 6 × (1:30 + 1:30) + 5:00 = 28 minutes. Adjust the work time to your actual pace — a 2-minute 400m means 120 seconds of work, not 90.
Audio cues
Beeps fire at every phase boundary:
- Warm-up → Work: high tone (880 Hz)
- Work → Rest: low tone (440 Hz)
- Rest → Work: high tone
- Rest → Cool-down: middle tone (660 Hz)
- Cool-down → Done: middle tone
You can work without looking at the screen — the pitch difference between the work-start beep and the rest-start beep is distinct enough that you know what phase is starting from the audio alone.
If your browser has blocked audio (some privacy setups do this by default) or you’re in a quiet environment where beeping would be disruptive, the on-screen display still shows the current phase, remaining time, and round number clearly.
What this tool does not do
It doesn’t handle non-uniform intervals — every round has the same work and rest duration. For complex protocols with varying interval lengths (pyramids, descending ladders), use a dedicated workout app or build the schedule manually.
It doesn’t persist workouts across sessions. Close the tab and the configuration is gone. If you use the same interval regularly, remember the numbers or save them in a note.
It doesn’t track heart rate, reps, or external performance metrics. It’s strictly a clock. If you want to log workout data, pair this with a fitness tracker or notebook. For timing a run without fixed intervals, the stopwatch captures lap times; for the classic 25/5 focus cycle, the pomodoro timer is the preset variant.