The best interval timer app for iPhone does 2 things: it keeps accurate time with the screen locked, and it tells you where you are in the workout without you picking it up. Everything else is preference, and a surprising number of timers in the App Store fail 1 of those 2 before you ever get to the preferences.
Both are things you can check yourself in about 5 minutes per app. Below are the 7 criteria that separate a timer you forget about from one you argue with, what a good version of each looks like, and the test that exposes it.
The 7 criteria, side by side
| Criterion | What good looks like | What bad looks like | The test |
|---|---|---|---|
| Locked screen accuracy | Cues land on schedule after minutes with the screen off | Drift that always gives you extra rest | Run 10 rounds of 30s, lock, wait 3 minutes |
| Music handling | Volume dips for the cue, playback continues underneath | Playback pauses at every boundary | Start a track, listen through one transition |
| Warning cue | 3 second countdown before every change | One beep, exactly on zero | Close your eyes through one work-to-rest change |
| Lock Screen presence | Live Activity with phase, round and seconds left | Nothing, or a notification per round | Lock the phone mid-round and look at it |
| Saved workouts | Named sessions, one tap to start | Re-typing 4 fields every session | Build a 12 round session, force quit, reopen |
| Free tier shape | Timing is free, extras are paid | Ads between rounds, or rest interval paywalled | Run one full session without paying |
| Wrist support | Optional, and standalone if it exists | A watch app that dies when the phone locks | Leave the phone in a bag for one round |
The first 4 decide whether the app is usable. The last 3 decide whether you keep it.
Does it survive a locked screen
This is the criterion that eliminates most of the field, and it is invisible in screenshots.
iOS suspends apps shortly after they leave the foreground, and it does so to protect battery. A timer built on a counter that increments once a second stops incrementing while suspended, so it resumes behind where it should be. On a 4 minute Tabata the drift is a second or two. On a 40 minute session it is embarrassing, and it always errs toward giving you extra rest, which is the direction that ruins the workout you thought you did.
The fix is structural. A timer should record the wall-clock instant the session started and answer every question by subtraction: given the time right now, which interval is this and how many seconds remain. Nothing is being counted, so nothing can fall behind. Suspend the app for 3 minutes and it returns exactly where the clock says it should be.
You cannot read this off a product page, so test it. Start a session, lock the phone, set a separate stopwatch, and compare the finish. Anything more than a second out over 10 minutes tells you what the app is doing internally.
Does it duck your music or stop it
Audio ducking means the app lowers your music volume for the moment its cue plays and lifts it back afterward. Your playlist keeps running underneath and you hear the beep over the top.
The alternative behavior pauses playback at every interval boundary. Across a 12 round circuit that is 24 interruptions, and on some setups the track does not resume on its own, so you reach for the phone. One session is enough to know which camp your current app sits in.
Once ducking is confirmed, 2 settings are worth a look. Cue volume that is independent of media volume, so you can push the beep above your headphone level without turning the music up. And a choice between a spoken count and a short tone, because speech gets lost under dense music while a high beep cuts through it.
Does it warn before the change or on the change
A cue that fires on zero arrives after the thing it describes has already begun. You hear the bell, register it, then stop, which means you either abandon a rep halfway or eat into the rest.
A 3-second countdown before every transition fixes it. Going into rest, you finish the rep you are in. Coming out of rest, you are back in position with your feet set before the work bell. In Tabata, where rest is only 10 seconds, this single detail is the difference between 8 honest rounds and 8 rounds where you arrive late to half of them.
Keep both cues. A warning tone at 3 seconds and a distinct tone on the transition itself, at a different pitch from the work tone, so you can tell from sound alone which state you are now in.
Live Activity and Dynamic Island
Live Activities put the running session on the Lock Screen, and Apple has supported them on every iPhone capable of running iOS 16.1 or later. The Dynamic Island version, which shows the same information around the front camera while you use other apps, needs an iPhone with a Dynamic Island: a 14 Pro, a 14 Pro Max or any iPhone 15 or newer.
You get a glance instead of a pickup. The phone lies on the bench, you look down between reps, and you see the phase, the round number and the seconds remaining without touching anything. If the Live Activity also carries pause and skip controls, you never leave the Lock Screen during a whole session.
Rounds is the iPhone interval timer I build, and this is the part it is designed around: the phase, the seconds left and the next movement live on the Lock Screen and in the Dynamic Island, with pause and skip right there. It computes the whole timeline from the wall clock for the reason described above. It is in open beta through TestFlight rather than on the App Store today.
Saved workouts and history
A timer that makes you re-enter work, rest, rounds and prepare every session is a calculator. Saved workouts turn a session into one tap, which matters most for the structures you repeat weekly: your 20/10 Tabata block, a 40/20 circuit, a 20 minute EMOM.
There are 2 things to check beyond the save button. Whether a saved workout can hold more than one block, so a warmup, a main set and a finisher live in one session rather than 3 timers you start by hand. And whether the app keeps a history of what you ran, because comparing round 1 to round 8 across weeks is where the training information actually is.
The free versus paid shape
Timing is cheap to build. 2 countdowns and a sound is a weekend project. So free timers are everywhere, and the stock Clock app gets close enough for a single countdown. Since iOS 17 the Clock app even runs several timers at once, though it still will not repeat a work and rest cycle on its own, so a Tabata means restarting timers 16 times.
That shapes what a fair paid tier looks like. Charging for the countdown itself is hard to justify; charging for saved workouts, history, sync across devices or integrations is straightforward. Rounds draws the line there: the timer, the presets and the Live Activity stay free, and the paid tier covers sync, routines and unlimited saved workouts.
The pattern to avoid is the ad interstitial between rounds. A free timer that shows you a full-screen ad at the changeover has taken away the one thing you installed it for, which is not having to touch the phone.
Apple Watch support
You probably do not. A phone on a bench with loud cues and a Lock Screen countdown covers the gym floor, the garage and the park, which is where most interval work happens.
A watch earns its place in 2 situations: a gym loud enough that audio fails, where wrist haptics still land, and any session where the phone is out of reach. If that is you, note that Apple’s Workout app on Apple Watch already builds custom workouts with warmup, cooldown, and repeating work and recovery intervals, with an Up Next view showing the current interval and what follows. That is a capable interval timer with nothing installed.
For third-party apps, ask whether the watch app runs the session itself or just mirrors the phone. A mirror stops being useful the moment the phone locks or wanders off, and that’s the moment you’d reach for the watch. App Store listings rarely say which kind they are. Rounds runs its own session on the wrist, so the phone can stay in a locker; the full picture of what a watch adds and what the built-in Workout app already does is worth reading before you install anything.
Run the 5-minute test
Install 2 candidates. Build the same session in both: 30 seconds of work with 30 seconds of rest across 10 rounds and a 10 second prepare. Start music. Start the timer, lock the phone, put it face down, and walk away for 3 minutes.
When you come back, check 3 things. Whether the cues are still on schedule against a second clock. Whether your music survived. Whether the Lock Screen told you where you were before you touched anything. The app that passes all 3 is the one to keep. The HIIT structures worth running on it don’t change with the app you pick.
Common questions
What is the best interval timer app?
The best interval timer app is whichever one keeps correct time with your phone locked and tells you where you are without being picked up. Test a candidate by starting a 10-round session, locking the screen, and putting the phone face down for 3 minutes. If the cues arrive on schedule and the Lock Screen shows the round and the seconds left, it passed the only 2 tests that matter.
What is the best free interval timer app for iOS?
Judge free iOS timers on what the free tier actually covers rather than the star rating. Timing itself is cheap to build, so a fair free tier gives you work, rest, rounds, prepare countdown and audio cues at no cost, and charges for saved workouts, history or sync. Watch for ad interstitials that appear between rounds, since an ad you have to dismiss mid-session defeats the point of a hands-free timer.
What is the best gym timer?
For gym floor use, pick the timer with the loudest distinct cues and a Lock Screen display with digits readable from 2 meters away. A gym is noisy, your hands are chalked or gripping a bar, and the phone is on a bench rather than in your hand. Distinct pitches for work and rest, a 3-second warning before every change, and a readable countdown on the Lock Screen cover almost everything you need.
Is there a free interval timer app for iPhone without a subscription?
Yes, several timers charge once instead of monthly, and some are free with ads. A single purchase suits a timer well, because the feature set stops changing once work, rest and rounds are handled. Subscriptions make more sense when the app syncs history across devices or keeps a server-side record, since that costs the developer money every month you use it.
Do I need an Apple Watch for interval training timers?
No. A phone on a bench with audio cues and a Lock Screen countdown handles interval work fine, and it is what most people use. A watch adds wrist haptics, which are useful in a loud gym or in a pool where you cannot hear anything. Apple's own Workout app on Apple Watch supports custom workouts with repeating work and recovery intervals, so you can run intervals on the wrist with no third-party app at all.
Should an interval timer warn before the change or on the change?
Before. A cue that fires exactly on zero is information you receive after the moment it described has already started, so you stop mid-rep or arrive late to the next work bout. A 3-second countdown before every transition lets you finish the rep you are in and set your feet. Keep a separate sound on the transition itself so you still know the exact instant it happened.