How to set an interval timer on iPhone or Android
The built-in Clock timer on iPhone counts down once and does not repeat, so for repeating work and rest you need an interval timer app. Decide four numbers first: work seconds, rest seconds, rounds and a warm-up. Then enter them once and start.
An interval timer repeats two phases, work and rest, for a set number of rounds. The Clock app that comes with your phone is a different kind of timer. Apple’s guide to the iPhone Clock says you can use the timer “to count down from a specified time,” choose a sound for when it ends, and that it continues “even if you open another app or if iPhone goes to sleep.” It describes one countdown and does not mention repeating or intervals.
On Android, Google’s Clock app counts down and can run several timers at the same time. We found no repeat or interval setting described for it, and phone makers such as Samsung ship their own clock apps that may differ. Check the Timer tab on your phone: if it asks for one length of time and has no field for rounds, it is a plain countdown.
A workaround is described further down.
Decide four things first
Before you open any timer, write down:
- Work time: how long you go hard, in seconds.
- Rest time: how long you recover.
- Rounds: how many times you repeat work then rest.
- Warm-up: a countdown before round one, so you can get into position. Ten seconds is typical for a single exercise.
The total is simple to calculate: (work + rest) times rounds, plus warm-up. Twenty on, ten off, eight rounds is 30 seconds times eight, which is 4:00 of work and rest. If you are not sure which numbers to pick, the guide to HIIT ratios walks through the common ones.
Set it up in an interval timer
The screens differ between apps, but the fields are the same. Most interval timers give you boxes for these values:
- Prep or warm-up: seconds before the first round.
- Work: seconds per work interval.
- Rest: seconds per rest interval.
- Rounds (or cycles): repeats of work and rest.
- Sets: some timers also let you repeat a group of rounds, with a longer break between sets.
Enter the numbers, press Start, and put the phone down where you can see it, or where you can hear it. Do a ten-second test run first, with 3 seconds on and 3 off, to learn the sounds and to check the volume.
Example 1: Tabata, 20 on, 10 off, 8 rounds
This is the classic. In the 1996 study that gave it its name, people trained on a stationary bike with 20 seconds of very hard exercise and 10 seconds of rest, seven to eight times a session. A bike at that intensity is a lot harder than most home Tabata workouts, so do not think of it as a gentle four minutes.
| Field | Value |
|---|---|
| Prep | 10 s |
| Work | 20 s |
| Rest | 10 s |
| Rounds | 8 |
| Total | 4:00 plus the 10-second prep |
Pick one exercise per block and keep it simple: squats, mountain climbers or a jump rope. If you want several exercises, run several blocks with a minute or two between them.
Example 2: 40 on, 20 off, 4 rounds, with a 2-minute break
This one suits a longer session with several moves.
| Field | Value |
|---|---|
| Prep | 10 s |
| Work | 40 s |
| Rest | 20 s |
| Rounds | 4 |
| Sets | 3, with a 2-minute break between |
One set is 4 minutes. Three sets with two 2-minute breaks make 12 + 4 = 16 minutes, plus prep. Use a different exercise in each round or the same four in each set. If your timer has no field for a longer break between sets, start the next set by hand after your two minutes.
Keep it running with the screen locked
A workout timer that dies when the screen turns off is a nuisance. Apple’s guide says the Clock timer continues when the phone sleeps, but that is about the Clock timer only. For any app:
- Start a short test, lock the screen, and wait for two cues.
- Make sure the sound comes through at the volume you use. Turn up the media volume and check what the volume buttons control while the timer speaks.
- If you play music, test with the music playing, because some timers stop it. This guide has a 30-second test.
If you want to build your own with Shortcuts
Apple’s Shortcuts app can repeat actions in a loop. Apple’s guide describes a Repeat action that runs the same actions multiple times. A shortcut that starts a timer, waits, and repeats is possible in principle, but we have not built or tested one, and each work and rest period would need its own step. For anything beyond a one-off, an interval timer is quicker to use.
Common problems
- No sound: check the media volume, and whether your phone is in a silent or Do Not Disturb mode that mutes the app. Settings differ between apps and phones, so run the ten-second test before the real workout.
- Cues are too quiet over music: see the music guide linked in the previous section, and prefer a timer that speaks.
- You keep looking at the screen: use a timer with big numbers, or voice cues, so that you can see or hear the phase from where you are exercising.
Setting this up in Countcall
Countcall has a quick timer with prep, work, rest, rounds and sets, and a one-tap Classic Tabata preset. In the quick timer the voice calls out the seconds and the phases (Work, Rest); saved workouts add exercise names. On Android, and on iPhone with iOS 17 or later, the timer sits on the lock screen. The app is not in the stores yet: join the waitlist below, and we will email you once when it is.
Questions people ask
Can the iPhone Clock app do interval timing?
Apple's iPhone User Guide describes the timer as a single countdown with an end sound, and says nothing about repeating. Apple's Shortcuts app can loop actions, so a workaround may be possible, but building one is a project in itself.
Can Android's Clock app repeat a timer?
We could not find a repeat or interval setting described for Google's Clock app, which counts down and can run several timers at once. Samsung and other makers ship their own clock apps, so check yours.
How do I set a Tabata timer?
Twenty seconds of work, ten seconds of rest, eight rounds. Add a warm-up before it. In an interval timer, enter 20 and 10, then 8 rounds.
Will the timer keep running when the screen is locked?
Apple's guide says the Clock timer continues when iPhone goes to sleep. With any interval app, lock the screen during a short test run and confirm the cues keep coming before a real workout.
How many rounds should I do?
It depends on the exercise and your level. A Tabata block is eight rounds, which is four minutes. For other ratios, see the guide linked below.