HIIT timer: 30/10, 40/20, 45/15.
Three classic interval shapes on one page. Pick one, press Start, and the beeps do the counting.
Free · runs in your browser · no sign-upGet ready
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Three short beeps count down each change; a long beep starts the next phase. The page keeps your screen on. If you lock the phone or switch apps, the browser can stop the beeps. The Interval Timer app keeps beeping with the screen off.
How to pick a ratio
| Shape | Work : rest | Rounds | Total | Feels like |
|---|---|---|---|---|
| 30 / 10 | 3 : 1 | 10 | 6 min 30 s | Little time to recover; keep the effort moderate |
| 40 / 20 | 2 : 1 | 10 | 9 min 40 s | The common class format; hard but steady |
| 45 / 15 | 3 : 1 | 8 | 7 min 45 s | Long work sets; good for circuits |
More rest lets you work harder in each round. Less rest keeps your heart rate up, but you will slow down. If your reps drop by more than a third from the first round to the last, give yourself more rest.
A circuit to try (no equipment)
Use 40 / 20 and 10 rounds. Do these five moves in order, twice through:
- Squats
- Push-ups (on your knees is fine)
- Reverse lunges
- Plank shoulder taps
- Jumping jacks
Use the 20 seconds of rest to get into position for the next move. The three short beeps tell you it is time to start.
Why the app, if the page works?
A web page runs only while its tab is open and the screen is on. Phones pause background tabs to save battery, so a browser timer can go quiet when you lock the screen or open your music app. This page asks the browser to keep the screen on, and it plans every beep ahead on the audio clock, so it stays on time while you can see it.
The Interval Timer app runs as a proper Android service. In our test on a Galaxy S23 it played 241 of 241 beeps in a 30-minute workout with the screen off and the phone in deep sleep, and the gaps between beeps were never more than 11 ms off. See how we measured it.
Questions
What does 30/10 mean in HIIT?
30 seconds of work, then 10 seconds of rest, repeated for a set number of rounds.
Is 40/20 better than 30/10?
Neither is better. 40/20 has twice as much rest per minute, so you can push harder in each round. 30/10 keeps you moving more of the time.
How many rounds of HIIT should I do?
8 to 12 rounds is common for one block. Beginners can start with 6 and add rounds week by week.
Can I change the times?
Yes. Type any work, rest and number of rounds below the presets. The total updates as you type.