Interval Training Timer
Run configurable work, rest and round intervals with transition beeps.
What this tool does
An interval training timer runs fixed work and rest periods for a set number of rounds, which is the structure behind HIIT, circuit training and any session that switches on a clock rather than on completion. This one shows the current phase, the time left in it, the round number and the rounds remaining, and beeps before each transition so you can change exercise without looking at the screen. Prepare, work, rest and rounds are all configurable, and a clear finish signal ends the session.
Runs configurable work, rest and round counts with a clear phase readout you can see mid-exercise.
Counts rounds down and the current interval within the round, so position is never in doubt.
Beeps before each transition and finishes with a distinct signal, usable without looking at the screen.
Adds a preparation countdown so the first work interval does not begin the instant you press start.
How to use it
- Set the prepare, work and rest durations.
- Set the number of rounds.
- Press start and follow the phase readout.
- Change exercise on the transition beep - no need to look.
- Reset or stop the session at any point.
Why use this tool
An interval training timer runs work, rest and rounds as a fixed schedule, and that structure is the entire method: the clock decides when to stop, not fatigue, not boredom, not the distance to the next lamp post. Free-form exercise drifts; intervals hold the ratio that makes the session count. The timer has to be readable mid-movement and audible across a room, because pausing a session to squint at a phone is how a 40-second work phase quietly becomes 25.
Why we built it
We built this interval training timer to count rounds down as well as the current interval, because during a session the question that actually matters is 'how many more of these'. The countdown timer covers a single period and the pomodoro timer the fixed work-break rhythm; this handles the repeated work-rest cycle with configurable ratios, and the multi timer handles everything that runs in parallel instead.
For keeping pace during the work interval itself, the metronome sets a cadence, and the online stopwatch is the plain count-up version.
Who this tool is for
- HIIT and circuit trainers working to fixed work-rest ratios
- Runners and rowers doing interval sessions indoors
- Coaches running a class through synchronized rounds
- Anyone whose training plan specifies seconds on, seconds off
When to use it
- Running a Tabata-style session of 20-second efforts.
- Doing a circuit with fixed stations and changeovers.
- Repeating sprint intervals with measured recovery.
- Any workout where the plan states work time, rest time and rounds.
How it works
The session is a schedule built from your inputs: prepare, then rounds of work and rest, in that order. The timer counts down each phase against the system clock, so a backgrounded tab keeps the correct remaining time. A warning beep sounds before each transition - one short beep for an upcoming change, and a longer distinct signal for the final transition into the last round and the end of the session. The readout shows the phase name, the time left, the round number and the rounds remaining together.
Browsers can throttle timers in background tabs and may block audio until you interact with the page. Keep the tab visible and allow sound when the session matters - the beeps are the part you use without looking.
Common ratios
| Format | Work | Rest | Rounds |
|---|---|---|---|
| Tabata | 20 s | 10 s | 8 |
| Classic HIIT | 30 s | 30 s | 10 |
| Sprint intervals | 60 s | 90 s | 6 |
| Circuit station | 45 s | 15 s | 12 |
| Beginner | 20 s | 40 s | 6 |
The ratios are starting points - shorter rest makes any session harder, and the timer exists so changing the ratio costs nothing but a new number.
A worked example
These are the values the timer opens with, so you can see how a session is put together. Change any setting on the page and the schedule rebuilds; the figures below describe the default.
| Phase | Duration | Count |
|---|---|---|
| Prepare | 10 s | once |
| Work | 30 s | 8 rounds |
| Rest | 30 s | 7 between rounds |
With those inputs, the session runs:
- Total time: 10 + 8 × 30 + 7 × 30 = 8 minutes
- Work time: 4 minutes of effort
- Rounds remaining counted down on every transition
- Beeps before each of the 15 transitions, plus the finish signal
What you enter, and what you get back
| Item | Details |
|---|---|
| Prepare, work, rest | Durations in seconds for each phase. |
| Rounds | How many work intervals to run. |
| Result | Live phase readout, rounds remaining, beeps and total session time. |
Issues you may run into
| What you see | Why it happens | What to do |
|---|---|---|
| No beeps | Audio blocked or tab muted. | Interact with the page once and allow sound. |
| Timer paused itself | Tab went to background. | Keep the tab visible during the session. |
| Session too hard | Rest too short for the work interval. | Lengthen rest or shorten work - the clock is yours. |
| Forgot which round | Looked away during transition. | The readout keeps round number and rounds remaining together. |
Assumptions and limitations
- Audio beeps require the browser to allow sound for the page, and background tabs may throttle the schedule.
- The timer counts down fixed intervals; it does not adapt to your pace or heart rate.
- Suggested ratios are common starting points, not training advice.
- Settings are held in the page for the session only unless the browser restores form state.
Frequently asked questions
What is a good work to rest ratio?
Common starting points are 1:1 for classic HIIT (30 seconds work, 30 rest), 2:1 for longer sprints (60 on, 90 off), and the strict 2:1 of Tabata (20 on, 10 off, 8 rounds). Shorter rest makes any session harder, so beginners do better starting at 1:2 and shortening the rest as fitness improves.
How do I set up a HIIT timer?
Enter your work seconds, rest seconds and number of rounds, add a short prepare countdown so you can get into position, then press start. The timer runs the schedule automatically, showing the phase, the time left and the round number throughout.
Can I add a preparation countdown?
Yes - the prepare phase runs before the first work interval, so the session does not start the instant you press start. Ten seconds is enough to get into position; the timer beeps to mark the end of preparation and the start of work.
How many rounds should I do?
Eight to twelve rounds of 20 to 45 seconds of work is a solid session for most people. Start at the lower end when beginning a new ratio, and let the rounds remaining readout carry the count so you can focus on the effort.
Does the timer beep between intervals?
Yes. A short beep warns of each upcoming transition, and a longer distinct signal marks the end of the session. The phase readout carries the same information visually, so the timer works in silence too.
Is the interval timer free?
Yes, completely free with no account and nothing uploaded. It runs entirely in your browser, and the beeps are generated locally with no audio files.