TimerPlanInterval timer
Interval timer
Work · round 1 / 8
0:40
- Whole session—
- Time working—
- Work : rest—
Rounds advance on their own — nobody is clicking mid-set. Space starts and pauses.
One thing a month worth timing
MonthlyOne thing a month worth measuring or capping with a clock — a payroll trap, a nap length, a meeting that never gets added up. Two sentences and the tool.
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How long is an interval session really?
The TimerPlan interval timer runs work and rest phases that advance on their own and shows the whole session length including the rest — eight rounds of forty seconds on and twenty off is eight minutes, not five and a half. The rest is a third of that session, and it is the part left out of every estimate.
Phases change without a click because there is nobody free to press anything mid-set. The display says which phase you are in and which round, and the sound marks the change so it works with the screen out of sight.
The work-to-rest ratio is on screen as trainers say it — 2:1, 1:1, 1:3 — because that ratio is what decides whether a session trains speed, conditioning or endurance. Changing the rest changes the session far more than changing the work does.
The settings that come up most, and what each one is:
| Work | Rest | Rounds | Total | Known as |
|---|---|---|---|---|
| 20s | 10s | 8 | 4:00 | Tabata |
| 30s | 30s | 10 | 10:00 | Even intervals, conditioning |
| 40s | 20s | 8 | 8:00 | The standard class round |
| 45s | 15s | 8 | 8:00 | Circuit, eight stations |
| 60s | 60s | 8 | 16:00 | Rowing and running repeats |
| 3m | 1m | 3 | 12:00 | Boxing rounds |
The last row is worth noting: boxing has used three minutes on and one off for over a century, and it is a 3:1 ratio — the same shape as a gym circuit, an order of magnitude longer.
For a session built from blocks of different shapes, the interval and HIIT plan adds them up before you start. For a single stretch with no phases, use the online timer, and for work-and-break cycles at desk scale the pomodoro timer counts rounds the same way. To record what actually happened — splits, fastest, average — the stopwatch is the tool that keeps them.
Frequently asked questions
What is the Tabata protocol exactly?
Twenty seconds of maximal effort, ten seconds of rest, eight rounds — four minutes in total. It comes from a 1996 study on the Japanese speed skating team, and it produced genuine aerobic and anaerobic gains at an intensity most classes never reach. Set 20s, 10s and 8 rounds here and the total shows the four minutes, which is the honest length of the protocol.
Does the timer keep running if my phone screen goes dark?
The page holds a screen wake lock while the session runs, so the display should not sleep on its own — which is the usual reason people give up on browser interval timers halfway through a workout. The sounds are scheduled in advance, so even a tab that gets frozen still marks the phase changes. A manually locked phone suspends the tab, and no web page can override that.
Why does my session take longer than the work adds up to?
Because rest counts, and at a 2:1 ratio it is a third of the total. Eight rounds of 40/20 is 480 seconds of which 160 is recovery. Anyone planning a session into a lunch break should use the total on screen rather than the work figure, and the interval plan under time plans adds several blocks together for a full session.
Should I use this or a countdown per exercise?
Use this when the structure repeats and a plain timer when it does not. A circuit of eight different exercises at 45/15 is one setting here; a session of unequal blocks — a warm-up, a main set, a finisher — is better built in the interval plan and then run block by block, since each block has its own shape.
How this works
Sources:
Reading the numbers
The ratio decides the session. 1:1 is conditioning, 1:2 or longer is speed, 2:1 and shorter is muscular endurance.
The total includes rest. It is the number that has to fit in the time you have.
Rounds advance themselves. The only interaction is start, and pause if something goes wrong.