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Stopwatch

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Stopwatch

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A free online stopwatch with millisecond precision

A stopwatch answers a different question from a timer. A countdown tells you when a duration you chose has run out; a stopwatch tells you how long something actually took. That distinction matters more than it sounds. You cannot improve a process you have never measured, and most people are surprisingly bad at estimating elapsed time — a task that feels like ten minutes is often twenty-five.

This stopwatch runs in your browser with nothing to install and no account to create. Open the page and press start. The main display shows hours, minutes and seconds in a large, readable format, with a separate millisecond readout underneath for when you need finer resolution than a second.

What the stopwatch gives you

Start, pause, resume

Pause whenever you are interrupted and resume from exactly where you stopped. Time accumulated before the pause is preserved, so a session broken into three stretches still shows the correct total.

Millisecond readout

Seconds are rarely enough when you are comparing two attempts at the same thing. The millisecond counter runs alongside the main display so you can see the difference.

Reset that asks first

Reset opens a confirmation dialog rather than wiping the screen instantly. A stray tap during a long session will not cost you the measurement.

Session history

Completed sessions are collected in a panel beside the stopwatch, so you can compare today against last week without writing anything down.

Readable at a distance

Large digits with a flip animation on each second mean you can read the time from across a room or a gym floor, not just from arm's length.

Works on any device

Desktop, laptop, tablet or phone, in Chrome, Safari, Firefox or Edge. Add the page to your home screen and it opens in one tap like an installed app.

When a stopwatch is the right tool

Sport and training

The obvious use is running, swimming and cycling, where the whole point is the number at the end. It is just as useful for the unglamorous parts of training: how long you actually held a plank, how long you really rested between sets, how long a warm-up takes when you stop rushing it. Coaches use one stopwatch across a whole session and compare the totals afterwards.

Work and process measurement

If you bill by time, or you are trying to work out where a day goes, measuring is the only honest way to find out. Time a support ticket, a code review, a deployment or a recurring admin task a handful of times and you will have a far better estimate than any guess. People preparing talks time their rehearsals to find out whether a twenty minute slot is really twenty minutes.

Study, practice and performance

Musicians time scale practice. Language learners time how long they can hold a conversation. Debaters and interview candidates time their answers because "keep it to two minutes" is meaningless until you have heard what two minutes sounds like. Timing a practice run before the real one removes most of the surprise.

Everyday curiosity

How long does the kettle take. How long is the commute really. How long can a child brush their teeth before giving up. A stopwatch turns a vague impression into a number, and numbers are easier to argue with.

Worked examples

A stopwatch is only useful once you decide what is worth measuring. These are concrete starting points — each one takes a single session to try, and each one tends to produce a number that surprises people the first time.

Three examples in full

Rest between sets

Start the stopwatch the moment you rack the bar and stop it when you pick it up again. Most people believe they rest ninety seconds and actually rest three to four minutes on the later sets, which quietly changes the workout they think they are doing. Two sessions of measuring is usually enough to fix it.

A rehearsal against a slot

You have a twenty minute talk. Start the stopwatch, deliver it out loud at real speed, and note the elapsed time at the end of each section rather than only at the finish. The overrun is almost never spread evenly — it is usually one section, and now you know which one to cut.

A recurring work task

Time the same admin job — a deployment, a support ticket, an invoice run — on four or five separate occasions. The spread between the fastest and slowest run tells you far more than the average does, and it is the honest basis for any estimate you give.

More things worth timing

What to timeWhat it tells you
A 5K or a lapThe obvious one. Splits matter more than the total — start the stopwatch once and read the elapsed time at each lap rather than resetting.
A plank or wall sitHeld positions are where estimation is worst, because effort distorts time. A measured 45 seconds beats an imagined two minutes.
A warm-upWarm-ups get rushed when nobody is watching the clock. Timing one honestly tends to add a couple of minutes back.
Scale or drill practiceMusicians and language learners both benefit from knowing whether "twenty minutes of practice" was twenty minutes or seven.
Your commuteTime the real door-to-door journey a few times instead of trusting the routing estimate, and plan against the slowest one.
The kettle, the boot time, the queueSmall everyday curiosities. Timing them once replaces a vague complaint with a number you can actually act on.

A practical habit for any of these: use pause rather than reset when you are interrupted. Resetting throws the measurement away, while pausing keeps the accumulated time and lets the session continue as one number.

How the timing works

Elapsed time is measured against your device system clock rather than by counting animation frames. That choice matters: frame counting falls behind whenever the browser is busy or the tab is in the background, and the error compounds over a long session. Working from the clock means the total stays correct no matter what else the machine is doing.

As with any browser tool, hidden tabs are drawn less often to save battery, so if you switch away the digits may appear to freeze and then jump forward when you return. The measurement itself is unaffected — only the display pauses.

  • Elapsed time is derived from the system clock, so it does not drift over long sessions.
  • Pausing stores the exact accumulated milliseconds rather than a rounded number of seconds.
  • Session history is written to your own browser storage, on your device, and never uploaded.
  • For everyday timing this is comfortably precise; officially certified race timing still needs dedicated equipment.

Frequently Asked Questions

Is this online stopwatch free to use?
Yes. The stopwatch is completely free, with no account, no sign-up and no paid tier. Open the page and press start. Advertising keeps the tool free for everyone who uses it.
How accurate is the stopwatch?
Elapsed time is measured against your device system clock rather than by counting animation frames, so the reading stays accurate over long sessions instead of drifting. The display shows hours, minutes and seconds, with a separate millisecond readout underneath for finer measurements. For everyday timing — workouts, cooking, study blocks, practice runs — it is more than precise enough. For officially certified race timing you would still want dedicated timing equipment.
Does the stopwatch keep running if I switch tabs or minimise the window?
Yes, the elapsed time keeps accumulating correctly. Because the total is calculated from the system clock, switching tabs, opening another app or locking your phone will not lose time. Browsers deliberately slow down hidden tabs to save battery, so the digits on screen may appear to freeze while the tab is in the background and will jump to the correct value as soon as you return to it.
Can I pause the stopwatch and resume it later?
Yes. Press Pause to stop counting and Resume to continue from exactly where you left off. The time you accumulated before pausing is kept, so you can break a session into several stretches and still see the correct total.
What happens if I press Reset by accident?
Reset asks for confirmation before it clears anything. A dialog appears asking whether you are sure, so a stray tap will not wipe a long session. Choose No to carry on where you were, or Yes to clear the display back to zero.
Does it remember my previous sessions?
Completed sessions are added to the history panel beside the stopwatch. That history lives in your own browser using local storage, on your device only — it is never uploaded to a server and we cannot see it. Up to 50 recent entries are kept, and you can delete individual entries or clear the whole list whenever you like.
Do I need to install anything to use it?
No. The stopwatch runs in the browser, so there is nothing to download or install and nothing to update. It works on desktops, laptops, tablets and phones, and behaves the same across Chrome, Safari, Firefox and Edge.
Does the stopwatch work on a phone?
Yes. The layout adapts to small screens, and the start, pause and reset controls are sized for touch. Many people add the page to their phone home screen so it opens in one tap, the same way an installed app would.
Should I use a stopwatch or a countdown timer?
Use a stopwatch when you want to find out how long something takes — timing a run, a chess move, a practice presentation or a work session you have not scheduled in advance. Use a countdown timer when you already know the duration and want to be told when it is up, such as a 25 minute Pomodoro or a 10 minute egg. Both are available free on this site.
Is my data collected or shared?
The stopwatch itself sends nothing to a server; your times stay in your browser. Like most free sites we use analytics and advertising cookies, and you are asked to consent to those before they are set. You can decline and still use every feature. Full detail is in our privacy policy and cookie policy.
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