What is an interval timer?
An interval timer alternates between work and rest on a fixed schedule and repeats that pattern for a set number of rounds. The whole point is that you don't have to think about timing at all - you just go hard during work, breathe during rest, and let the timer handle the structure. Once you start, it auto-advances through every phase until the session is done.
Timglas turns the schedule into something you can see across the room. The hourglass empties for the current phase, a clear badge shows whether you're in work or rest, the round counter ticks down, and a sound plus a screen flash mark every transition. The screen stays awake throughout, so a phone propped up on a kitchen stool keeps showing the right thing right through the workout.
Quick-pick presets
Four well-known interval formats, ready to load with one tap. Pick one to get going, then tweak the work, rest, and round counts to match your session.
Tabata - 20s / 10s × 8
The classic four-minute Tabata protocol. Twenty seconds of all-out effort, ten seconds of rest, eight rounds. Short, brutal, and proven - pick a single exercise (squats, burpees, mountain climbers) and go as hard as you can each work phase.
HIIT - 30s / 15s × 8
The everyday HIIT default. Long enough to get a real working set, short enough that the rest isn't a full recovery. Pairs well with bodyweight circuits, kettlebell swings, or sprint intervals on a stationary bike.
EMOM-style - 45s / 15s × 10
A lighter take on every-minute-on-the-minute work. Forty-five seconds on, fifteen off, ten rounds - long enough for a meaningful set of reps, with built-in pacing. Good for building work capacity without redlining.
Language drills - 60s / 30s × 6
Sixty seconds to recall a flashcard or run through a verb conjugation, thirty to flip the card and reset. Six rounds is roughly the limit before fresh attention helps more than another rep - switch decks rather than chasing more rounds.
When the interval timer earns its keep
Reach for the interval timer whenever your work-rest pattern is fixed and you want to stop watching the clock. It's especially useful when you need to:
- Run a HIIT or Tabata circuit without counting in your head between rounds.
- Drill skills (musical scales, vocabulary, kata) on a steady cadence so the rhythm becomes automatic.
- Cycle through language flashcards with a fixed think-then-flip pace.
- Pace any task that benefits from forced rests - even short coding bursts with breathing breaks.
How to use it
A handful of taps and you're off:
- Pick a preset - Tabata, HIIT, EMOM-style or language drills - or set your own work, rest and rounds in the inputs below.
- Press start. The first work phase begins; the hourglass tips over and the round counter starts at one of N.
- Each phase auto-advances. When work ends you'll hear a cue and the timer flips into rest; when rest ends it flips back to work - no taps, no typing.
- Pause any time, skip a phase if you finished early, or reset to start over. When the final work phase ends, a completion screen shows the totals.
Frequently asked questions
How does a round work exactly?
A round is one work phase plus the rest that follows it. With 30 seconds of work, 15 seconds of rest, and 8 rounds, you'll do work-rest-work-rest eight times - except the very last rest is dropped, so the session ends the moment the eighth work phase finishes. That mirrors how most people actually train: once the final set is done, you're done.
What's the difference between Tabata and HIIT?
Tabata is a specific protocol - 20 seconds of work, 10 seconds of rest, exactly 8 rounds, four minutes total - designed for all-out effort on a single movement. HIIT is the broader category of high-intensity interval training; it includes Tabata but also longer work-to-rest ratios like 30/15 or 45/15. Use the Tabata preset for a single intense exercise, and the HIIT preset when you're cycling through a circuit.
Will it work with the sound off?
Yes. Each phase transition triggers a desktop notification, a brief screen flash, and a screen-reader announcement, in addition to the audio cue. The hourglass is always visible, the phase badge always says where you are, and the round counter always ticks. A configurable completion sound is on the roadmap.
Can I pause or skip a phase?
Yes - pause stops the current phase wherever it is and waits for you to press start again. Skip jumps straight to the next phase, which is handy if you finished a rep set early or just need to move on. Reset rewinds the whole session back to round one. Editing the work, rest, or rounds inputs is disabled while the timer is running so the schedule stays predictable.