Run work and rest rounds with clear sound beeps, so you can train hard without watching the clock. Set your intervals and rounds in seconds.
High-intensity interval training works because it is short, sharp, and structured. You work hard for a fixed time, rest for a fixed time, and repeat. The hard part is not the exercise; it is watching the clock while you are out of breath. This free HIIT interval timer runs the work and rest rounds for you, with sound beeps at every change, so you can focus on moving, not counting.
The default is a classic starter session: 30 seconds of work, 15 seconds of rest, repeated for 8 rounds, which takes six minutes. That is enough for a real workout in a lunch break, and short enough that most people finish it. Change the numbers to match your fitness: beginners can start with 20 seconds of work and 40 of rest, while fitter users can flip that ratio.
How to run a session
- Set the work seconds, the rest seconds, and the number of rounds.
- Press Start. The timer shows the current phase, the seconds left, and the round number.
- Work when the phase says Work, and rest when it says Rest. Two beeps mark each change, and three beeps mark the finish.
- Press Pause if you need a longer break, and Reset to start over with new numbers.
The beeps matter more than they seem. During a hard interval you may not be looking at the screen, and a phone timer that only vibrates is easy to miss over music. A clear beep tells you to switch without breaking your rhythm, and the round counter tells you how much is left, which is often the difference between quitting at round five and finishing round eight.
Building a simple HIIT workout
- Pick four moves: for example squats, push-ups, mountain climbers, and jumping jacks, one per round, repeated twice.
- Keep moves simple: complex moves fall apart when you are tired. Simple moves stay safe at speed.
- Warm up first: two minutes of easy marching and arm circles before the timer starts. Cold muscles and sprints do not mix.
- Cool down after: walk and stretch for two minutes when the three beeps sound.
Progress slowly. Add one round per week, or add five seconds of work, but not both at once. If you cannot speak a short sentence during the rest periods, the work intervals are too long or the rest is too short. A session that leaves you wrecked for two days was too much; a session you can repeat three times a week is about right.
Honest limitations
First, this timer counts time; it does not coach form, count repetitions, or track your heart rate. If an exercise hurts in a sharp or joint-specific way, stop: pain is not part of the program. Second, the sound depends on your browser staying awake, so keep the screen on during the session and test the beeps before you start. Third, HIIT is intense by design. People with heart conditions, asthma, pregnancy, or injuries should check with a doctor before starting interval training.
Finally, a timer cannot replace a plan. Use it for short sessions a few times a week, alongside walking and rest days, rather than hammering hard intervals every day. Recovery is where fitness is built.
Frequently asked questions
How long should a HIIT session be?
Between 10 and 25 minutes including warm-up and cool-down is plenty for most people. Longer sessions usually mean the intensity has dropped, and at that point it is no longer HIIT.
How many rounds should a beginner do?
Four to six rounds of 20 seconds work and 40 seconds rest is a kind first session. Add rounds gradually over weeks, not in one day.
Does the timer keep running if I switch apps?
The timer uses your device clock, so short switches are fine, but if the browser tab is fully suspended, the beeps may be delayed. Keep the tab visible during the session for reliable sound.