Interval Timer
Set a work time, a rest time and a number of rounds -- or pick a HIIT or Tabata preset -- and get an audible cue at every transition, hands-free.
Round 1 of 8 · Work
Total workout time: 03:50.
The presets, worked out
| Preset | Work / rest | Rounds | Total time |
|---|---|---|---|
| Tabata | 20s / 10s | 8 | 03:50 |
| HIIT | 40s / 20s | 8 | 07:40 |
| Boxing rounds | 180s / 60s | 6 | 23:00 |
| EMOM-style | 30s / 30s | 10 | 09:30 |
Every total in that table comes from the same function the running timer above calls to compute its own "total workout time" line -- change the fields on the timer and that line updates to match.
How the round sequence is built
A schedule with N rounds alternates work, rest, work, rest, ... ending on the Nth round's work block with no trailing rest. Internally, each block just replays the same exact-timestamp countdown method every other timer on this site uses: an end time is set the instant a block starts, and the remaining time for that block is always today's time subtracted from that end time -- never a running tick count that could fall behind if a frame gets dropped mid-workout.
If a round is set to zero-second rest
Setting rest to 0 seconds skips the rest phase entirely rather than inserting a blink-and-you-miss-it round -- the timer moves straight from one work round's alarm cue into the next work round, useful for something like an EMOM (every-minute-on-the-minute) structure where the "rest" is really just whatever time is left in the work interval once the set is done.
Frequently Asked Questions
What's the difference between Tabata and HIIT on this timer?
Tabata is a specific, well-defined protocol: 20 seconds of work, 10 seconds of rest, for 8 rounds (4 minutes total) -- originally studied by Dr. Izumi Tabata in the 1990s. "HIIT" (high-intensity interval training) is a broader category that Tabata falls under; the HIIT preset here uses a more forgiving 40-seconds-work / 20-seconds-rest split for 8 rounds, a common variation for a longer, slightly less extreme session.
Why is there no rest after the last round?
There's nothing left to rest before -- the schedule this timer builds always ends on a work round, so the total time is exactly (work x rounds) + (rest x (rounds − 1)), not rest x rounds.
Can I set my own work/rest/rounds instead of using a preset?
Yes -- the three fields under the presets are fully editable; picking a preset just fills them in as a starting point. Changes apply the next time you press Start.
Does this timer pause between rounds for me to catch my breath, or keep going automatically?
It keeps going automatically -- every transition (work to rest, rest to work, and the final round to done) is hands-free, with its own audible cue, so you never have to touch the screen mid-workout. If you need a real pause, the Pause button stops the clock exactly where it is.
What sound plays at each transition?
A short synthesized beep plays between work and rest (in both directions); a longer chime plays once, at the very end of the last round, so "workout complete" is unmistakably different from an ordinary round transition.
Every timer here runs entirely in your browser -- nothing you set is sent anywhere. The countdown display isn't a substitute for a certified stopwatch or a safety-critical timing device; see the Terms.