Build an interval timer app you can read and hear from across the room
Mid-workout, you can't tap small buttons or read small numbers. An interval timer app has to be glanceable from three metres away and audible over music, and it must never lose its place. Anticode can build a HIIT or Tabata timer with your own routines, sounds generated in the browser, and a display designed for sweaty hands.
The building blocks of an interval workout
Nearly every interval format is a combination of a few values. Get the model to treat a workout as data built from these, and one app covers Tabata, EMOM, circuits and running intervals:
| Format | Work | Rest | Rounds and sets |
|---|---|---|---|
| Tabata | 20 s | 10 s | 8 rounds, often repeated in sets with a minute's rest |
| EMOM | The reps, inside each minute | Whatever's left of the minute | 10 to 20 minutes |
| Circuit | 40 s per station | 20 s to move | 6 to 10 named stations, 2 to 3 laps |
| Running intervals | 2 min hard | 1 min easy | 6 rounds plus warm-up and cool-down |
Add a warm-up and cool-down phase, and a prepare countdown (usually 10 seconds) before the first round so you can put the phone down and get into position.
A screen for a sweaty workout
- The phase is the colour. Full-screen green for work, blue or grey for rest, amber for the last three seconds. Colour reads from far away when numbers don't.
- Huge, fixed-width digits. Seconds remaining fill most of the screen in landscape.
- Context in small type. Round 5 of 8, next exercise, total time remaining.
- One giant control. Tap anywhere to pause. Skip and back as large buttons at the edges, never tiny icons.
- Named stations. For circuits, the current and next exercise in words: "Kettlebell swings, next: plank".
Sound without sound files
Anticode's apps can't load audio files from anywhere, so beeps are generated in code with the browser's Web Audio API. That's well suited to timers: short tones at three, two and one, a longer tone at the switch, a distinct pattern at the end of the workout. Ask for different pitches for work and rest so you know which is starting without looking.
Test on your own phone before relying on it. Browsers only allow audio after a tap, which the Start button provides; and the phone's silent switch or volume settings can mute a web page. A spoken "rest" voice isn't something to count on either, so lean on distinct tones and colours.
Keeping the right time
Phones throttle timers when the screen locks. Ask for the timer to work from the clock, recording when each phase should end, so it stays correct after the screen has been off. Then test: start a workout, lock the phone for a minute, unlock it and check it moved on to the right round. If the screen dimming is a problem mid-workout, change the phone's auto-lock setting for the session.
Describing your timer
"An interval timer app for my garage gym. Saved workouts I can create and edit: name, prepare 10 s, warm-up, list of stations with work and rest times, laps, cool-down. Built-in presets for Tabata and a 40/20 circuit. Landscape full-screen display, green for work, slate for rest, amber for the last 3 seconds, huge numbers, station names. Beeps made in code at 3-2-1 with a different pitch for work and rest. Tap anywhere to pause." Saved workouts stay in that browser on that device.
What it doesn't do
- No heart rate. It can't connect to a watch or chest strap.
- No music control. It can't pause your music app or duck its volume.
- No coach-led sessions across devices. A class where everyone's phone follows the instructor's timer needs a server; each device here runs its own.
- No workout logging across devices. History, if you add it, stays on one device. For tracking sets and weights over months, see the workout tracker app.
For a single countdown to a time or a stage slot, the countdown timer app page covers the different design. A gym that wants a timer on its own wall screen can run this full-screen in a browser; the digital signage app page covers screens that run all day.
Questions people ask
Can the interval timer app speak the exercise names?
Don't count on spoken audio inside the sandbox. Ask for it if you like and test it, but design around tones and on-screen names.
Will it work in airplane mode?
The timer itself needs no network once it's open. Installed published sites also have an offline fallback; test your routine offline before you need it.
Can I share my workouts with a friend?
Ask for an export of a workout as a short code or file they can import into their own copy.