Free HIIT Timer for iPhone

The simple, ad-free interval timer for high-intensity interval training

What is HIIT?

HIIT (High-Intensity Interval Training) alternates short bursts of intense exercise with recovery periods. A typical HIIT session lasts 15 to 30 minutes and can burn more calories than traditional steady-state cardio in less time.

HIIT works with any exercise: running, cycling, bodyweight movements, kettlebells, or gym machines. The key is pushing hard during work periods and recovering during rest. A reliable interval timer is essential to keep the structure tight.

Why Box Timer for HIIT?

• Flexible intervals — Set any combination of work time, rest time, and rounds. From quick 15-second sprints to longer 45-second circuits.
• Loud audio cues — Beeps at every transition so you know exactly when to push and when to rest, even with headphones off.
• Works with your music — Keep your workout playlist going. Timer sounds mix with your audio instead of cutting it off.
• Screen stays on — The display stays awake during your workout so you can always glance at the time remaining.
• Workout history — Sessions are saved automatically. Name and pin your go-to HIIT workouts for one-tap reuse.
• No ads, ever — No interruptions between rounds. No subscriptions. No premium tier. Just a timer.

How to set up a HIIT timer

1. Open Box Timer and tap Edit Timer
2. Select Interval as the timer type
3. Set Rounds to your desired number
4. Set Work time (e.g. 0 minutes and 30 seconds)
5. Set Rest time (e.g. 0 minutes and 15 seconds)
6. Turn on Countdown for a 10-second lead-in
7. Tap Save, then Start

See the full guide: How to set an interval timer with both work and rest time

Popular HIIT formats

All of these can be set up in Box Timer using the interval timer mode.

Related: Free Tabata Timer for iPhone  ·  Best Workout Timer Apps for iPhone in 2026  ·  HIIT & Interval Timer Guide