⏱️HIIT Timer Online
A free hiit timer online — set your own work and rest durations, rounds, and sets, with audio cues and screen wake lock. Press start and focus on your workout.
20 s work × 10 s rest × 8 rounds × 1 set = 4 min session
Configure your session above, then press Start.
This tool provides general information and is not medical advice. Exercise intensity should match your own fitness and health. Please consult a physician before starting a new exercise routine or training at high intensity—especially if you have any heart condition, injury, or health concern.
Free HIIT Timer Online
Ready to sweat? Our free HIIT Timer runs your high-intensity interval workouts the moment you press start. As a clean, distraction-free hiit timer online, it alternates timed work and rest periods, counts your rounds, and signals every switch — so you can push hard and let the timer keep track instead of watching the clock.
But it does more than count down. Set your own work and rest durations, choose how many rounds and sets you want, and rely on clear audio cues that sound even with your phone tucked away. The screen stays awake so your session never stops mid-round, and a bold current-phase display shows whether you're working or resting at a glance. Whether it's Tabata-style or your own custom routine, it adapts to you.
Simply set your intervals and press start. No sign-up, no downloads, no limits — just a clean interval timer whenever you need it. See the FAQ for common questions, or read more about how it works.
What is HIIT?
High-intensity interval training (HIIT) alternates short bursts of intense effort with brief recovery periods. The work intervals push your heart rate up while the rest intervals give your body a partial recovery before the next effort. This contrast — working hard then recovering, repeatedly — is what makes HIIT efficient: you accumulate more high-intensity output in a given session than you could manage without the rest breaks.
The most famous format is Tabata: 20 seconds of all-out effort followed by 10 seconds of rest, repeated 8 times for a 4-minute set. The timer defaults to this configuration but you can customise every parameter to suit your training — longer work intervals, more rest, more rounds, or multiple sets.
About the HIIT Timer
The HIIT concept
High-intensity interval training alternates between two effort levels: a work phase where you push hard — sprinting, cycling fast, or doing high-output bodyweight exercises — and a rest phase where you recover at a much lower intensity or stop completely. The contrast is what makes HIIT effective: you accumulate more high-intensity output in a session than you could sustain continuously.
The Tabata protocol (20s on, 10s off × 8) was developed by Japanese researcher Dr Izumi Tabata and is the most studied HIIT format. The timer defaults to Tabata but the settings accept any combination so you can follow your own programme or coach's prescription.
Key features
Audio cues via Web Audio API
At each phase transition the timer plays distinct audio signals — three ascending tones to signal the start of a work interval, two descending tones for rest, and a three-note chime when the session ends. These use the Web Audio API so they play reliably even when the screen is locked or the tab is in the background.
Screen Wake Lock
On browsers that support the Screen Wake Lock API, the timer requests a wake lock when you press Start so the display stays on throughout your session. The lock is released when you pause, reset, or the session finishes. On unsupported browsers the timer still runs normally and audio cues still fire.
Custom intervals, rounds, and sets
Set work and rest durations in seconds, choose the number of rounds per set, and set how many sets you want. Three built-in presets (Tabata, 30/30, and 40/20) let you start quickly. Settings lock while a session is running to prevent accidental changes mid-workout.
Phase and progress tracking
A bold phase display shows WORK or REST at a glance. The countdown shows the time remaining in the current phase, a progress bar fills across the phase, and the round, set, and total elapsed time are updated every second so you always know where you are in the session.
Who it's for
Tabata training
The default settings match the classic Tabata protocol exactly. Press start and follow the audio cues without watching the screen.
Circuit training
Set longer work intervals (30–60s) with short rests between exercises, and multiple sets for a full circuit session.
Home workouts
No equipment or gym needed. Set your intervals, put your phone to the side, and let the audio cues tell you when to push and when to rest.
Custom programmes
If your coach prescribes specific work/rest ratios, rounds, and sets, dial them in directly. The timer handles any combination.
A note on health advice
Frequently Asked Questions
What is a HIIT timer?
A HIIT (High-Intensity Interval Training) timer alternates short bursts of intense work with rest periods, signalling each switch so you can focus on the workout instead of watching a clock.
How does the HIIT timer work?
Set your work and rest durations and the number of rounds, press start, and the timer counts down each interval, plays an audio cue at every switch, and tracks your progress through the session — hands-free.
Is this timer free to use?
Yes, it's completely free with no sign-up, downloads, or limits. Use it for as many workouts as you like.
Can I customise the work and rest times?
Yes. You can set your own work and rest durations in seconds, the number of rounds per set, and the number of sets — or use a built-in preset like Tabata (20 seconds work, 10 seconds rest, 8 rounds).
Will the audio cues play if my screen is off or phone is in my pocket?
Yes. The timer uses the Web Audio API so cues sound reliably even when the screen is locked or the tab is in the background.
Does the screen stay on during a workout?
On supported browsers the timer uses a screen wake lock to keep the display awake so your session isn't interrupted. On browsers that don't support it, the timer still runs and the audio cues still play.
Can I pause and resume a session?
Yes. You can start, pause, resume, and reset at any time. The timer picks up exactly where you left off when you resume.
Is my data stored anywhere?
No. The timer runs entirely in your browser and doesn't store or send any personal data to a server.
Does it work on mobile devices?
Yes, the timer is fully responsive and designed for use on a phone during a workout, as well as on tablets and desktops, with the display fitting the screen without overflow.
Is HIIT suitable for everyone?
HIIT is intense by design. It's popular and effective, but the right intensity depends on your fitness and health. If you're new to exercise or have any health condition, check with a doctor before starting — this tool is a timer, not medical advice.