This online timer works as a stopwatch: it counts up from zero in hours, minutes, seconds and tenths, lets you record lap times while it keeps running, and needs nothing to install. The page below also explains how elapsed time is converted between seconds, minutes and hours, because that conversion is where most mistakes happen.
How to use the timer
- Press Start to begin. The button changes to Stop.
- Press Lap to record a split without stopping the clock. The newest lap appears at the top with its own duration and the running total.
- Press Stop to pause; press Resume to carry on from the same time.
- Press Reset to clear the display and the laps.
Timer formula: seconds to hours, minutes and seconds
Minutes = ⌊ (seconds mod 3,600) ÷ 60 ⌋
Seconds = seconds mod 60
Lap time = current total − previous total
The stopwatch measures the real time since you pressed Start rather than counting screen updates, so it stays accurate even if the page is busy. Hours keep counting past 24 instead of wrapping around.
Example: converting 3,723.4 seconds
- 3,723.4 ÷ 3,600 = 1 hour, with 123.4 seconds left over.
- 123.4 ÷ 60 = 2 minutes, with 3.4 seconds left over.
- Result: 01:02:03.4, that is 1 hour, 2 minutes and 3.4 seconds. In decimal form, that is 62.0567 minutes or 1.0343 hours.
Use the converter in the calculator fields to try any number of seconds.
Seconds, minutes and hours reference
| Seconds | As a clock | Minutes | Hours |
|---|---|---|---|
| 30 | 00:00:30.0 | 0.50 | 0.0083 |
| 90 | 00:01:30.0 | 1.50 | 0.0250 |
| 300 | 00:05:00.0 | 5.00 | 0.0833 |
| 1800 | 00:30:00.0 | 30.00 | 0.5000 |
| 3600 | 01:00:00.0 | 60.00 | 1.0000 |
| 5400 | 01:30:00.0 | 90.00 | 1.5000 |
| 7200 | 02:00:00.0 | 120.00 | 2.0000 |
| 86400 | 24:00:00.0 | 1440.00 | 24.0000 |
Good ways to use a stopwatch
- Workouts and running: record a lap at each kilometre or mile and compare your pace as you go.
- Cooking: time steeping, resting and proofing without watching the clock.
- Work and study: log how long a task takes so that future estimates are realistic; many people work in 25-minute blocks.
- Presentations: practice a talk and note the lap at each section.
Timer or countdown?
A stopwatch counts up from zero; a countdown timer counts down from a target and alerts you at the end. If you know how long you want — an egg, a meeting slot, an exam — the Countdown Timer is the better fit. To work out what time a duration will end at, use the Minutes From Now Calculator or Hours From Now Calculator calculators. Adding up shifts? Try the Time Card Calculator.
Frequently asked questions
How do I use the online stopwatch?
Press Start to begin counting up, Lap to record a split time without stopping, Stop to pause and Reset to clear everything. The display shows hours, minutes, seconds and tenths.
Does the timer keep running if I switch tabs?
Yes. The stopwatch compares the current time with the moment you pressed Start rather than counting display updates, so it stays accurate even if the browser slows down background tabs.
How do I convert seconds to hours, minutes and seconds?
Divide the seconds by 3,600 for hours, take the remainder and divide by 60 for minutes, and what is left over is the seconds. 3,723 seconds = 1 hour, 2 minutes, 3 seconds.
What is the difference between a lap and a split?
A lap time is the time for one segment; a split (or cumulative) time is the total since the start. This timer shows both.
How accurate is the stopwatch?
It is accurate to well under a tenth of a second for everyday use, but it depends on your device’s clock and is not intended for official sports timing.