HIIT Interval Timer
Build a work-and-rest countdown with phase labels, round count, pause and reset.
Your inputs
HIIT Interval Timer
600 seconds total
00:10:00
Full result table
| Component | Total seconds |
|---|---|
| Warm-up | 0 |
| Work | 400 |
| Recovery | 200 |
| Cool-down | 0 |
Final recovery is included. The page does not recommend an exercise intensity or continue an alarm after closure. Work + recovery is included for every round, including final recovery. Timer requires this page to remain open.
Let’s work it out.
Ask about this tool, enter your values, or understand your result.
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How to use HIIT Interval Timer
- Enter work interval (seconds), rest interval (seconds), rounds, warm-up seconds, cool-down seconds.
- Calculate and compare the labelled result views. Check that every input uses the displayed unit.
- Read the worked example and limits before applying the answer.
Worked example
10 rounds of 40 seconds work and 20 seconds rest total 10 minutes.
Formula, accuracy & limitations
Duration is entered directly, or rounds × (work + rest) for interval timers.
Final recovery is included. The page does not recommend an exercise intensity or continue an alarm after closure. Work + recovery is included for every round, including final recovery. Timer requires this page to remain open.
Calculations use your inputs. Main numeric values show up to six decimal places, percentages up to two, and chart labels up to four. Time results use hours, minutes and seconds. Very small nonzero values use scientific notation.
Build one interval plan rather than separate timer pages
Set work seconds, recovery seconds, rounds and optional warm-up and cool-down. A round includes work and recovery, including recovery after the last work interval. Zero recovery removes recovery phases. The total plan is limited to 24 hours.
Start the clock deliberately
Press Start after the calculation. Pause preserves elapsed progress; Resume continues the same plan and Reset timer returns to its beginning. Editing inputs invalidates the old plan until a new result is ready. Keep the page open; this is not an alarm service after browser closure or a medical exercise prescription.
Frequently asked questions
Is final recovery included?
Each round includes its recovery, including the last round. Warm-up and cool-down are additional optional phases.
Does closing the page keep the timer running?
The countdown is page-local and stops being available when the page is closed. It does not schedule a background alarm.
Will the countdown keep working when I leave this page?
The page must stay open. Browser background throttling can delay screen updates; the countdown reconciles elapsed time when the page updates again.
What happens when I edit the plan during a countdown?
The old plan is invalidated. Calculate the updated plan and start it again so the countdown phases match the inputs shown.
