How to set up an interval workout
- Type your Work and Rest times:
40means 0:40,1:30is a minute and a half, and3mis three minutes. - Set Rounds, and Sets if you repeat the block; Rest between sets appears from two sets on.
- Add a Warm-up and a Cooldown if you want them; 0:00 skips them.
- Check the line under the fields, such as “Total 9:50 · 10 rounds · 1 set”.
- Press Start. During the workout, Space pauses, → and ← jump between segments, and L locks the screen.
Timeline lists the start time of every segment if you want to check the plan first.
Work, rest, rounds and sets explained
A round is one work period followed by its rest. A set repeats your rounds, and Rest between sets gives you a longer break after each set. Skip rest after the last round (on by default) ends the workout, or the cooldown, right after the final work period. Whatever form of interval training you follow, the total updates as you type:
| Workout | Program | Total |
|---|---|---|
| HIIT | 40/20 × 10 rounds | 9:50 |
| HIIT, two sets | 40/20 × 10 × 2 sets, 1:00 between | 20:30 |
| Circuit | 45/15 × 8 rounds × 3 sets, 1:00 between | 25:25 |
| Run/walk | 1:00 run / 2:00 walk × 8 | 22:10 |
All totals include the 10-second warm-up.
Beeps and offline voice cues
With Countdown beeps on 3-2-1, three short pips count down to every change and a long pip marks the switch itself. Halfway beep adds a ding in the middle of each work period, and a bell rings when the workout is done. Voice cues reads out each phase with a voice installed on your device, so nothing is sent to a speech service. If your device has no offline English voice, Settings tells you, and you still get every beep.
Big color screens for the gym floor
Each phase fills the run view with its own color and word: amber for GET READY, red for WORK, green for REST, blue for SET REST and indigo for COOLDOWN. Press Fullscreen and turn the phone sideways for a workout timer you can read from the floor; the word moves left and the time right. Lock ignores stray taps from sweaty hands until you hold the button for a second.
Save and share your programs
Save program asks for a name of up to 30 characters and keeps the program in My programs, up to 20 of them, in this browser only. Load one before a session, rename it or delete it; Undo brings a deleted program back. Share → Copy link sends the times and counts to a training partner. The link never includes the name.
Options explained
- Countdown beeps: 3-2-1 (default) or Off; the long pip at each switch stays either way.
- Halfway beep: off by default.
- Voice cues and Voice: off by default; the list shows offline voices only.
- Volume: 70 % by default; M mutes.
- Keep screen on, Show time in tab title and Show progress in tab icon: all on, so a background tab shows “0:17 · Work 3/10”.
How it stays in sync
Your program becomes a timeline of start times. The timer’s position is the time since you pressed Start, minus any pauses, read from your device clock rather than counted ticks. Beeps are scheduled ahead on the audio clock: 10 seconds ahead while the page is visible and up to 10 minutes ahead in a background tab, where browsers slow down timers. If your device stops the page, the timer jumps to the right phase when it wakes and offers to go back. See how our timers stay accurate.
Tips and limits
- Keep the page in front with the screen on; a locked phone pauses web pages.
- Bluetooth speakers and headphones can delay beeps slightly.
- On a PC or an Android phone, any modern browser works.
- For 20/10 × 8 with no setup, use the Tabata timer. For 3-minute rounds with a bell, open the boxing round timer. To repeat a single minute, try the 1 minute timer; to time a for-time finisher, a stopwatch counts up.
FAQ
What is an interval timer and how does it work?
An interval timer switches between work and rest for the number of rounds you set, so you never watch a clock mid-exercise. This one turns your program into a timeline of start times, reads its position from your device clock and books every beep ahead of time, so the switches stay on time.
How do I set an interval timer for HIIT?
The page opens on a common HIIT setup: 40 seconds of work, 20 seconds of rest, 10 rounds and a 10-second warm-up, 9:50 in total. Change Work, Rest or Rounds to fit your session, check the total under the fields and press Start.
What is the difference between rounds and sets?
A round is one work period plus its rest. A set is a group of rounds, and Rest between sets adds a longer pause after each group. Ten rounds of 40/20 in two sets with 1:00 between them take 20:30, including the 10-second warm-up.
Can the workout timer speak the intervals?
Yes, if your device has an offline voice. Switch on Voice cues in Settings and you hear phrases such as "Work, round 3 of 10" and "Rest" right after the long beep. Only voices installed on the device are used; without one, you get beeps only.
Will it keep running with my phone on the floor?
Yes, as long as the page stays open and the screen stays on; the timer asks your phone to keep the screen awake where the browser supports it. If the phone locks, the page pauses. When you unlock it, the timer jumps to the right phase and offers to go back.
Can I save and share my workouts?
Yes. Save program keeps up to 20 named programs in this browser under My programs, ready to load, rename or delete. Share → Copy link creates a link with every time and count of the program; the name stays private, and the link never starts the timer on its own.
How do I use an interval timer on iPhone?
Open the page in Safari and tap Start, which also unlocks sound. Fullscreen fills the window because Safari can't hide the page completely. Keep Safari in front: the screen stays on from iOS 16.4, or 18.4 when the page is added to your Home Screen.
Is this interval timer free?
Yes, it is free with no account or app to install. Your programs and settings stay in this browser, nothing about your workout is sent to a server, and once the page has loaded it keeps working offline, so a weak gym connection doesn't stop the workout.
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