Interval Timer

How to use the interval timer

1. Tap a preset: Tabata (20 s work, 10 s rest, 8 rounds), HIIT 40/20, EMOM (a new interval at the top of every minute), 30/30 or Run/walk. Or tap Custom and set your own.
2. Change any interval: type seconds (45) or minutes and seconds (1:30). Add Sets to repeat the block with a rest between, and a warm-up or cool-down around it.
3. Optionally type your exercises, one per line, and switch on Spoken cues to hear the round and the exercise.
4. Tap Start. The screen fills with the countdown; Pause, Skip and Back are at the bottom (space, right arrow and left arrow on a keyboard).
5. Save the workout to find it here next time, or Copy share link to send it to a training partner.

How the workout is put together

The timer lays your workout out as a row of intervals: the warm-up, then for each set a work interval and a rest for every round, then the cool-down. The rest after the last round of a set is left out where a rest between sets or the cool-down takes its place, so you never get two rests in a row. Tabata keeps its last 10 s rest, so 8 × (20 + 10) is exactly 4:00, with a change of interval at 20, 30, 50, 60 … 240 seconds.

Worked example: a 60 s warm-up, 3 rounds of 40 s work and 20 s rest, 2 sets with 60 s between them and a 60 s cool-down. Each set is 3 × 40 + 2 × 20 = 160 s, so the whole workout is 60 + 160 + 60 + 160 + 60 = 500 s (8:20). At 2:05 into it you are 5 s into the second work interval of set 1, with 35 s to go.

The time on screen is worked out from the moment you pressed Start, not by counting timer ticks, so a busy or dimmed phone does not slow it down, and an accidental reload picks up where you were. The beeps are booked a second or so ahead on the browser's audio clock, which runs separately from the page, so they land on the second rather than whenever the page gets round to them. While a workout runs the page asks the browser to keep the screen on (Screen Wake Lock) where the browser offers it.

What it cannot do

• A phone may pause a web page when the screen locks or you switch apps. The time stays right and catches up when you look again, but beeps and spoken cues that fall while the page is paused are not played late. Keep the page open on screen.
• Spoken cues use the voices your device has; how they sound, and whether there is a voice at all, depends on the device and browser.
• No heart rate, no calories, and no fitness or health advice: it times the intervals you set. It does not play music.
• Vibration only works on phones and browsers that offer it; many do not.
• Up to 100 rounds, 20 sets, intervals of up to 60 minutes and 50 exercise names.

Privacy and what is stored

Nothing you type leaves your device. Saved workouts, your beep and voice settings, and the workout that is running (so a reload can resume it) are kept in this browser's local storage; Clear saved workouts deletes all of it in one tap. A share link carries the workout inside the part of the address after #, which browsers do not send to the server; opening one fills in the fields as a copy and saves nothing until you press Save. The page sends an anonymous page-view count and, at most, two fixed words (interval-start and interval-share-open), never an exercise or a time.

Questions

Can I use this interval timer online without an app?

Yes. It is a web page: open it in the phone, tablet or laptop browser you already have, pick a preset or set your own intervals and tap Start. There is no account and nothing to install. Once the page has loaded it keeps timing even if the connection drops.

How do I set up an interval timer for my workout?

Set Work and Rest in seconds (or minutes like 1:30), the number of Rounds, and optionally Sets with a rest between them, a Warm-up and a Cool-down. Type your exercises one per line: the timer uses them in order, one per round, starts again at the top when the list runs out, and shows the next one during each rest. Save the workout on this device or copy a share link.

Can I use it as an interval timer for running?

Yes. The Run / walk preset is 1 minute running and 2 minutes walking, ten times, between a 5-minute warm-up and a 5-minute cool-down (38 minutes). Turn on spoken cues to hear Run and Walk with the round number. Keep the page open on screen: a phone that locks may pause the page, so the beeps can stop until you look again.

Does the timer work with sound?

Yes. Three short beeps count down the last 3, 2 and 1 seconds of every interval and a higher beep marks the start of the next one; they are scheduled ahead on the browser's audio clock, so they land on time even when the page is busy. Spoken cues (Rest, Round 3 of 8, the exercise name) are optional and use your device's own voices. If you hear nothing, check the volume and the phone's silent switch.

Why does a Tabata timer have 8 rounds?

The protocol comes from a 1996 study by Izumi Tabata's group, in which seven subjects did seven to eight bouts of 20 seconds of very hard cycling (about 170 % of their VO2max) with 10 seconds of rest between them. Eight rounds of 20 + 10 seconds is 4 minutes exactly, which is what the Tabata preset runs; add Sets to repeat the block.