Online Stopwatch
Measure elapsed time with precision — start, stop, lap, and reset in one click.
What is it?
An **online stopwatch** measures the time that elapses from the moment you press start to the moment you press stop. Unlike a countdown timer that works backward from a set time, a stopwatch starts at zero and counts upward — making it the right tool whenever you need to measure how long something takes rather than how long until something happens. Stopwatches are indispensable across an enormous range of activities. Coaches time athletes during training sessions. Cooks measure how long a steak sears before flipping. Developers benchmark how long a function takes to execute. Teachers time student presentations. Runners measure their lap splits. And anyone who has ever needed to know "how long did that take?" has reached for a stopwatch. This free, browser-based stopwatch displays hours, minutes, seconds, and hundredths of a second. It records lap times with a single keypress, stores a full session history, and calculates the fastest and slowest laps automatically. All timing happens in your browser with no server involvement — just open the page and start timing.
How to use it
- Click "Start" or press Space to begin timing.
- Click "Lap" or press L to record a lap time without stopping the stopwatch.
- Click "Stop" or press Space again to pause the timer.
- Click "Reset" to clear the time and all laps back to zero.
- Review your lap history in the table below — fastest and slowest laps are highlighted automatically.
Why use this tool
Your phone has a stopwatch, but it requires unlocking, navigating to the Clock app, and finding the right tab — all while whatever you are timing keeps going. This stopwatch is one click away in your browser, already visible on your screen, and ready to go the moment you need it. The keyboard shortcuts (Space to start/stop, L for lap) mean you can time things without taking your eyes off what you are measuring. The lap table with automatic best/worst highlighting makes it easy to spot patterns in performance data at a glance. For coaches, athletes, and anyone doing interval training, the lap system is especially valuable: each split is timestamped and the session can be easily reviewed after the fact.
Frequently asked questions
How accurate is this stopwatch?
The stopwatch uses the browser's high-resolution timing API (performance.now()), which is accurate to sub-millisecond precision. The displayed resolution is hundredths of a second (10ms). For everyday timing purposes, this is more than sufficient.
Will the stopwatch keep running if I switch tabs?
Yes. The timing logic continues to work correctly even when the tab is not active. When you switch back, the displayed time will be accurate.
Is there a maximum time this stopwatch can measure?
The stopwatch can measure durations up to 99 hours, 59 minutes, 59 seconds, and 99 hundredths. This covers virtually any real-world timing need.
Can I export my lap times?
Yes. Use the "Copy laps" button to copy all recorded lap times to your clipboard as plain text, which you can then paste into a spreadsheet or notes app.
What is the difference between a stopwatch and a countdown timer?
A stopwatch starts at zero and counts up, measuring how long an event takes. A countdown timer starts at a set duration and counts down to zero, alerting you when time is up. Use a stopwatch when you need to measure elapsed time; use a countdown timer when you need to enforce a time limit.