Interval Timer Online — HIIT, Tabata, Boxing & Custom Workout Sequences
Stop searching for a timer that actually fits your workout. Whether you need a classic Tabata, a custom HIIT sequence with warm-up and cool-down, a boxing round timer for 12 rounds, or a live countdown to your next race day — this tool handles all of it in one place, with no app download or account required.
Build any multi-phase sequence, pick how many loops, hit Start, and the timer handles the rest: correct phase, correct duration, correct sound. Works entirely in your browser, even offline once loaded.
How to Use the Interval Timer
Choose between two modes at the top of the tool: Interval Timer for workout sequences, or Countdown to Date for event countdowns.
Interval Timer mode
- Edit your phases — Each row is one phase: click the colored dot to change the phase color, edit the name inline, and set the duration in MM:SS format (e.g.
00:40for 40 seconds). Add phases with the "+ Add Phase" button. - Set your loops — Choose how many times the full sequence repeats: 1, 2, 3, 5, 8, 10, or ∞ for infinite. The total workout time updates live below the phase list.
- Pick a preset or start — Click any built-in preset (Tabata, HIIT, Boxing, etc.) on the right panel to load it instantly. Or hit Start to begin your custom sequence — the display switches to a full-screen-ready timer with a progress bar, current phase badge, and next phase preview.
- Share or save — Hit Share to copy a shareable URL that encodes your full timer config. Hit Save Preset to store it locally in your browser for future sessions.
Countdown to Date mode
- Enter event details — Type the event name and pick the target date and time.
- Start the countdown — Hit "Start Countdown" to see a live DD / HH / MM / SS display updating every second.
- Share the link — Hit "Share Link" to copy a URL anyone can open to see the same countdown running live.
Interval Timer Examples
| Protocol | Sequence | Total |
|---|---|---|
| Tabata | Work 20s / Rest 10s × 8 loops | 4 min |
| HIIT 30-30 | Work 30s / Rest 30s × 20 loops | 20 min |
| Boxing Amateur | Round 2 min / Rest 1 min × 3 loops | 9 min |
| Boxing Pro | Round 3 min / Rest 1 min × 12 loops | 48 min |
| MMA Round | Round 5 min / Rest 1 min × 5 loops | 30 min |
| EMOM 10 min | Work 40s / Rest 20s × 10 loops | 10 min |
| Study Sprint | Study 45 min / Break 10 min × 3 loops | 165 min |
Edge case — infinite loops: Set loops to ∞ for open-ended sessions like yoga or stretching. The timer continues until you manually reset it.
Edge case — single phase: A single-phase timer works fine — useful for a simple rest timer between sets where you only need one countdown.
Interval Training Protocols — What They Are
Tabata alternates 20 seconds of maximum-effort work with 10 seconds of rest, repeated 8 times for exactly 4 minutes. Developed by Dr. Izumi Tabata, the protocol was shown to improve both aerobic and anaerobic capacity simultaneously — more efficiently than steady-state cardio for the same time investment.
HIIT (High-Intensity Interval Training) is the broader category. Any structured work-to-rest ratio counts as HIIT. Common ratios: 1:1 (30s/30s), 2:1 (40s/20s), and 3:1 (45s/15s). Tabata is technically a specific form of HIIT.
EMOM (Every Minute on the Minute) means completing a set of reps at the top of each minute, resting for whatever time remains. Faster reps = more rest. The timer counts within each 60-second window.
AMRAP (As Many Rounds As Possible) uses a fixed total time window with no built-in rest — the athlete decides when to rest within the clock.
Boxing rounds: Amateur: 2 minutes of work, 1 minute rest, 3 rounds. Professional: 3 minutes work, 1 minute rest, up to 12 rounds. The preset configures this automatically.
Common Use Cases
- CrossFit WODs: Tabata, EMOM, and AMRAP sessions with precise round timing and sound cues for group classes.
- Gym circuit training: Multi-exercise circuits with transition time between stations and a rest period between rounds.
- Martial arts: Boxing, MMA, and Muay Thai round timers with bell sounds separating rounds from rest.
- Yoga and mobility work: Bilateral stretches with a short "switch side" cue between left and right, looped for full sessions.
- Event countdown: Race day, competition, travel, holiday — a live countdown you can bookmark and share.
- Study intervals: Study sprints with structured break time without the Pomodoro restriction of fixed 25-minute blocks.
Frequently Asked Questions
What is an interval timer and how does it work?
An interval timer alternates between multiple timed phases and repeats them for a set number of loops. You define each phase name, duration, and color — the timer handles the transitions automatically, plays a sound at each phase change, and shows you which phase is next. This is fundamentally different from a simple countdown because it manages a full structured sequence, not a single duration.
What is the difference between HIIT and Tabata?
Tabata is a specific HIIT protocol: exactly 20 seconds of work and 10 seconds of rest, repeated 8 times for 4 minutes total. HIIT is the broader category — any structured high-intensity interval training qualifies, regardless of the work-to-rest ratio or duration. You can do HIIT with 30/30, 45/15, or any other ratio; Tabata is always 20/10 × 8.
Does the interval timer work offline?
Yes — once the page has loaded, all timer logic runs locally in your browser using JavaScript. No server requests are made during a session. If you lose your connection after the page loads, the timer continues working normally.
Can I save my custom workout preset for next time?
Yes. Click Save Preset, give it a name, and it's stored in your browser's localStorage — no account needed. Your saved presets appear in the "My Presets" panel and persist across sessions on the same device. They are not synced to other devices.
Does it work in fullscreen mode?
Yes — during an active timer session, click the expand icon in the top-right corner of the display to request fullscreen via the browser's native fullscreen API. This is ideal for gym floors, CrossFit boxes, or group classes where participants need to see the timer from a distance.
What do the sound alerts mean?
A double sharp beep signals the start of a work/exercise phase. A single soft tone signals a rest or recovery phase. Three quick ticks fire 4 seconds before the current phase ends. A rising arpeggio (C-E-G chord) plays when the full workout is complete. All sounds are generated by the browser's Web Audio API — no audio files are downloaded.
Resources
- NSCA — Interval Training Guidelines — evidence-based recommendations for work-to-rest ratios across different training goals.
- Tabata Protocol — Original Research (PubMed) — Tabata et al. 1996 study showing the protocol's effectiveness for aerobic and anaerobic conditioning.
