An interval timer has one job. Make the switch impossible to miss.
Work ends, rest starts, and you should know both without checking. The board above runs a get-ready count, then alternates work and rest for the rounds you set. Add a long rest every few rounds when the plan needs a reset. Each change gets its own sound, or its own spoken word if you switch voice on.
The strip under the digits draws the whole session to scale. A three-minute boxing round looks three times longer than the one-minute rest beside it, so you see the shape of the workout before you commit to it. The clock reads real elapsed time, not a counter, and your last setup stays in local storage on this device.
Nothing is uploaded.
Ratio first, format name second
Work to rest is the real setting. Tabata, HIIT, and EMOM are labels for popular ratios. Two to one, forty seconds on and twenty off, suits bodyweight circuits. One to two or one to three suits sprints, because quality falls apart when you start the next effort still gasping. One to one for twelve rounds looks easy on paper and is not. No rest at all is a single long effort, so leave the rounds out and time it on a stopwatch.
| Preset | Work / rest | Rounds | Clock time | Where it goes wrong |
|---|---|---|---|---|
| Tabata | 0:20 / 0:10 | 8 | 3:50 | The research behind the name used near all-out effort on a stationary bike. At half effort it is a warm-up with a famous name. |
| HIIT | 0:45 / 0:15 | 12 | 11:45 | Twelve rounds punish a fast start. Begin at a pace you would still hold in round twelve. |
| EMOM | 0:40 / 0:20 | 10 | 9:40 | A real EMOM ends the work when the reps end. A timer cannot count reps, so work is fixed at 40 seconds. |
| Boxing | 3:00 / 1:00 | 5 | 19:00 | Matches the three-minute round. There is no ten-second warning clap, so watch the strip. |
| Circuit | 0:30 / 0:10, 1:00 every 3 | 9 | 7:30 | Three stations, three laps. The long rest is the walk to the next station. |
| Sprints | 0:30 / 2:00 | 6 | 13:00 | Cutting the rest to one minute turns speed work into conditioning. Pick which one you want. |
Twelve minutes before the next meeting? Tap HIIT, prop the phone at eye level, and press Start before you pick up the mat.
The last rest is missing on purpose
The session ends on the final work block. Nobody needs fifteen seconds of standing around after the last burpee, so the clock does not add them. A long rest replaces the normal rest after every Nth round, never after the last.
If your program counts a closing rest, as the classic four-minute Tabata does, the total here reads 3:50. Add ten seconds in your head, or run one extra round at a walk.
Learn six sounds, then stop looking
- One beep
- Get-ready count starts. 600 Hz.
- Two notes rising
- Work starts. 740 Hz, then 1100 Hz.
- Two notes falling
- Rest starts. 660 Hz, then 440 Hz.
- Three notes falling
- Long rest starts. 520, 390, then 300 Hz.
- Short ticks
- The last three seconds of a block. 1000 Hz.
- Three notes rising
- Session finished. 660, 880, then 1320 Hz.
Six sounds. That is the whole vocabulary.
Spoken cues use the speech engine built into your device. Voice, accent, and delay depend on the operating system, so test it once before a session. It says the phase and the round, and it calls out the last round. Tones and voice play together, so switch tones off if two signals feel loud in a small room. Volume applies to both. At zero the board keeps running in silence as a plain visual timer.
Tabs, screens, and the clock
The loop checks the clock four times a second and works out which block you belong in from the time elapsed since you pressed Start. If the browser freezes the page for ninety seconds, the next tick lands in the correct block. It does not replay the missed cues. You hear the cue for where you are now. Hidden tabs are the weak spot. Browsers cut a background tab's timer wake-ups to save battery, and after several minutes hidden, Chrome stretches them to as little as once a minute. The tab title carries the remaining time and the phase, for example 0:23 Rest, so a glance at the tab strip confirms the clock.
Pause freezes elapsed time and Resume continues from the same second. Back returns to the start of the current block, or to the previous block if you are inside its first two seconds. Skip jumps to the next block. Reload the page and the running session is gone. Only the setup stays.
Keys during a session: Space pauses and resumes, N skips, B goes back, Escape stops. Space does nothing while the timer is idle, so scrolling this page never starts a workout.
Three sessions, timed
- Living room, ten minutes. Tap EMOM. Pick five moves and give each one two rounds. Every rising cue means switch move. The total is 9:40 after the countdown, which leaves room to reset the mat between the fifth and the sixth round.
- Heavy bag. Tap Boxing and turn spoken cues on, because gloves cannot touch a phone. Prop the screen at eye height. Round four is where most people start dropping their hands, so watch how many segments are left on the strip.
- Hill sprints. Tap Sprints and walk down as the two-minute rest. A phone in a pocket locks its screen and stops the cues, so leave it on a bench with the screen on. Set Keep screen on and check that the battery is not in saver mode.
What this timer will not do
It does not count reps, read your heart rate, or judge whether twenty seconds all-out suits your body. It times blocks, nothing more. If you are new, start at one to two work to rest, stop when form breaks, and ask a doctor before hard intervals if you have a heart or joint condition.
Limits exist. Each block tops out at 59:59, a long rest at 30:00, and the round count at 99. Inside those limits, nothing stops you from building a session longer than your battery, so read the total under the strip before you press Start.
When a different timer fits
A single plank hold or one ninety-second set does not need rounds. Use the countdown timer for a target moment, or the timer with alerts for a labeled length with a system notification. Study blocks with a break rhythm, 25 on and 5 off, suit the Pomodoro timer, which is built around focus blocks instead of effort blocks. Planning a session that has to finish at a set clock time? Work out the length with the duration calculator first, then enter it here.