Online Stopwatch
Free fullscreen stopwatch — laps, keyboard shortcuts, 1/100 s accuracy.
How to use the stopwatch
Press Start or the space bar to begin. Press Lap (or L) to record split times without stopping the clock. Press R to reset. Press F for fullscreen — ideal for classrooms, workouts and presentations.
| Action | Key |
|---|---|
| Start / Pause / Resume | Space |
| Record a lap | L |
| Reset | R |
| Fullscreen | F |
Why this stopwatch is drift-free
Many web stopwatches count animation frames, and browsers pause or slow those in background tabs — so a “2-minute” stopwatch can end up showing 1:40. StopwatchHQ instead derives elapsed time from your device's system clock timestamps. Switch tabs, minimize, cover your phone screen: the displayed time stays exact to the hundredth of a second.
Use cases
- Classrooms — fullscreen timing for quizzes, debates and exams visible from the back row.
- Workouts — time sets and rest periods, then review your lap list to see rep pace.
- Lab & cooking — record split times for multi-step processes without touching the mouse.
- Presentations — keep speakers on schedule with a big, readable clock.
Stopwatch vs countdown timer: which one do you need?
The two tools answer opposite questions. A stopwatch counts up from zero when you press start: use it when the duration is unknown in advance, like timing how long a task actually takes, recording a commute, or measuring a child's homework session for a week to see the real average. A countdown timer counts down from a set duration: use it when the time is already decided, like a 10-minute exam section or a 45-minute parking limit. If you catch yourself setting a stopwatch and then trying to "beat" a mental target, you probably wanted the timer.
Lap times vs split times
The lap list records both numbers for every press. The split is the total elapsed time at that moment; the lap is the time for just that segment, since the previous press. Think of a 4 × 400 m relay: the splits are each runner's cumulative time, the laps are each runner's own leg. When you want to compare pace across repetitions, read the lap column, it is already doing the subtraction for you, and the fastest and slowest laps are highlighted automatically.
Why web stopwatches drift (and why this one doesn't)
Browsers render pages with animation frames, typically 60 per second, and aggressively pause those frames in background tabs to save battery, sometimes to one update per second or less. A stopwatch that counts frames therefore runs slow whenever you look away. The correct design, used here, never counts frames at all: every redraw simply reads the device's system clock and subtracts the start timestamp. The cost of a throttled background tab is a stale display for a moment, never a wrong total. The same engine powers every tool on this site.
A short history of the stopwatch
Portable timekeeping before the 19th century meant pocket watches with second hands but no way to stop and restart the dial. The breakthrough came in 1816, when the Swiss watchmaker Louis Frédéric Perregaux built the first true chronograph, started and stopped with push-pieces, initially to time horse races. King Louis XVIII of France famously watched races at the Champ de Mars while a watchmaker timed them for him. Electronic timing arrived with the 1932 Los Angeles Olympics, where mechanical stopwatches were paired with a photo-finish camera for the first time; today's finish times are measured in thousandths of a second by cameras that would look alien to those officials. The browser stopwatch you are using descends directly from that lineage: a start timestamp, an elapsed calculation, and a display big enough to read at a glance.
Getting times out of the page
Lap lists live on the page, and nothing is uploaded anywhere. If you need the numbers for a spreadsheet or a training log, the quickest routes are: read them straight from the list after the session (each lap shows split and segment), take a screenshot in fullscreen mode, or log each rep into the time tracker with a description, which gives you a dated, exportable CSV of every timed block.
Related tools
Need an alert when time is up instead? Try the online countdown timer. Working in focused sprints? The pomodoro timer runs the classic 25/5 cycle. Training in intervals? The interval timer handles work/rest automatically.