Interval timer
A work/rest interval timer for workouts.
The interval timer alternates between a work phase and a rest phase for a set number of rounds, counting down each phase and switching automatically — the browser tab's title updates with the remaining time so you can glance at it without watching the page directly.
Work
00:30
Round 1 of 8
How to use
- Set your work seconds, rest seconds, and number of rounds.
- Click "Start" — the timer alternates between work and rest phases, counting down each one, until every round is complete.
- The page title updates with the remaining time, so you can glance at a browser tab instead of watching the page directly.
Common use scenarios
- Running a structured interval workout (like a Tabata-style routine).
- Timing repeated work/rest cycles for any kind of practice or drill.
- Keeping consistent timing across multiple rounds without manual counting.
- Getting an audible-adjacent cue (via the tab title) between phases while looking elsewhere.
✓Content & verification reviewed: 2026-08-25
How we verify Interval timer
How to confirm the timer is tracking your workout correctly.
Rounds alternate work then rest, ending after the last work phase's rest
Each round consists of one work phase followed by one rest phase — the timer only marks all rounds complete after finishing the rest phase of the final round, not immediately after the last work phase.
Changing settings while running doesn't retroactively change the current phase
Work seconds, rest seconds, and rounds are locked while the timer is running (the inputs are disabled) — pause or reset first if you need to change your settings mid-session.
The tab title cue only works while the tab is open
The countdown continues in the title only as long as this browser tab exists — closing it, or the device sleeping for a long time, can affect timing, so treat this as a training aid rather than a precision lab timer.
Before you rely on the result
- Your work seconds, rest seconds, and rounds are all set correctly before starting.
- You understand a round finishes after its rest phase, not right after the work phase.
- You've paused or reset before changing settings, since inputs lock while running.
- You're keeping the tab open and your device awake for accurate timing during a session.
Who this is for
- Anyone running a structured interval workout.
- People timing repeated work/rest cycles for practice or drills.
- Anyone wanting consistent timing across rounds without manual counting.
- People who want a glanceable cue via the tab title while looking elsewhere.
Real-world examples
Tabata-style workout
Someone doing a classic 20-seconds-work, 10-seconds-rest routine sets those values with 8 rounds and starts the timer, following the on-screen phase and countdown.
Custom practice drill
A person practicing a skill in short bursts sets a longer work phase and a shorter rest phase to match their own training structure.
Hands-free phase awareness
Someone exercising away from their screen keeps the browser tab visible in the background, glancing at the tab title's countdown to know when a phase is about to change.
Limitations
- Runs only while this browser tab stays open — switching away for a long time or letting the device sleep can pause the countdown, so it's a training aid, not a precision lab timer.
Frequently asked questions
When does the timer consider all rounds complete?
After the rest phase of the final round finishes — not immediately after the last work phase ends.
Can I change the rounds while it's running?
No — the work seconds, rest seconds, and rounds inputs are locked while the timer runs. Pause or reset first to change them.
Does the timer make a sound?
It updates the browser tab's title with the remaining time and current phase — there's no audio alert, so keep an eye on the tab if you're relying on the title cue.
Will it keep accurate time if I lock my phone or switch apps?
Not reliably — it depends on the browser tab staying active. Treat it as a training aid rather than a precision timer for anything requiring exact timing.
🔒 Runs in your browser — nothing is uploaded. Results are for reference only; see the disclaimer. Last updated: 2026-08-25
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