Main tool

Run your interval session

Use a preset for a fast start or customize every interval below. Time values are entered in seconds and rounded to whole seconds.

Ready

Current stage

00:20

Round 0 of 8 Next: Work

The timer is set to the first stage in your current plan and has not started yet.

Total workout time 07:00 Warm-up and cooldown included when their values are above zero.

Interval pattern 20s work / 10s rest 8 rounds, 20s warm-up, 30s cooldown.

Setup

Customize the timer

Every field is validated immediately. Invalid values keep the timer from starting so you do not begin with a broken interval plan.

Warm-up (seconds)

Use `0` to start directly with the first work interval.

Work interval (seconds)

Must be at least 1 second.

Rest interval (seconds)

Use `0` for continuous rounds without a rest stage.

Rounds

Whole rounds only. Values are coerced to integers.

Cooldown (seconds)

Use `0` to end immediately after the last work or rest stage.

Playback options

Auto-start the next stage after each transition. Play a short tone when a stage ends. This uses your browser audio settings.

Current plan: 20 seconds warm-up, then 8 rounds of 20 seconds work and 10 seconds rest, followed by 30 seconds cooldown.

How it works

What the timer is doing

The timer converts your settings into an ordered list of stages. Warm-up and cooldown are optional, rest is skipped automatically when set to `0`, and the last stage finishes cleanly without negative time or broken transitions.

1. Build the sequence

Each plan becomes `warm-up -> work/rest rounds -> cooldown`. Rounds are always counted as whole numbers.

2. Run one stage at a time

The large timer shows only the current stage. The summary line below it tells you the next stage before the switch happens.

3. Keep the math reliable

Inputs are clamped to safe ranges, empty values are rejected, and total duration is recalculated before every run.

Workout timing is informational only and is not medical guidance. Adjust intensity for your condition, stop if you feel unwell, and use a qualified trainer or clinician when needed.