Interval Timer

How to use

1. 1Pick a preset like Tabata 20/10, HIIT 30/30, EMOM 60s, or Boxing rounds, or skip the presets and build your own pattern below.
2. 2Set the Prepare countdown, Work seconds, Rest seconds, and Rounds per set. Add Sets and a Long rest if you want a circuit-style session.
3. 3Press Start (or hit Space). The first cue plays, the progress ring fills as the phase elapses, and the tab title shows the remaining time.
4. 4Use Pause (Space) to interrupt, Skip phase (S) to jump to the next block, and Reset (R) to clear back to the start. Toggle sound cues or 3-2-1 countdown beeps from the side panel.
5. 5When the final round ends, a triple-tone plays and the timer shows Session complete. Press Start again to repeat the same workout.

About this tool

Interval Timer is a configurable workout timer that runs alternating Work and Rest blocks across a set number of rounds, with an optional prepare countdown at the start and an optional long rest between sets for circuit-style training. It covers the protocols people search for: Tabata (20s work, 10s rest, 8 rounds), classic HIIT (30/30 or 40/20), EMOM (60s work, 0s rest), boxing rounds (3 minutes work, 1 minute rest, 12 rounds), and any custom shape you build. The countdown is anchored against the browser's monotonic clock (performance.now), so the timer stays accurate even when the tab is throttled, the device sleeps briefly, or rAF callbacks coalesce; time is recomputed from the anchor on every animation frame instead of being decremented step by step. A circular progress ring around the time shifts color by phase (rose for Work, emerald for Rest, amber for the long rest between sets, blue for the prepare countdown) so the current state is readable across the room. Audible cues play through the Web Audio API with no external sound files: a rising two-tone for Work, a descending tone for Rest, a short tick for the final 3 seconds of each phase, and a celebratory triple-tone when the session finishes. Keyboard shortcuts cover Space (start and pause), R (reset), and S (skip phase), and the document title updates with the remaining time and phase so the timer stays glanceable from a background tab. Six quick presets cover the common shapes: Tabata 20/10, HIIT 30/30, HIIT 40/20, EMOM 60s, boxing 3-minute rounds, and a 3-set circuit. The custom panel lets you set prepare, work, rest, rounds, sets, and long-rest seconds independently, and the live summary shows the total session length so you know exactly how long the workout will take. Useful for high-intensity intervals, Tabata protocols, EMOMs, circuit training, jump-rope rounds, sparring and pad work, kettlebell sets, mobility work between heavy lifts, sprint intervals on a bike or treadmill, breath-work routines, and any session where a structured rhythm of work and rest beats watching a clock. Everything runs locally in your browser: no signup, no synced session data, no audio uploads, and no analytics tied to your workouts.

Free to use. Works in your browser. No signup, no login.