daytics™
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About the Stopwatch
Our online stopwatch uses high-resolution timestamps for millisecond accuracy. It continues running accurately even when the browser tab is in the background. Lap times are recorded with each lap highlighted as fastest or slowest.
How to Use the Stopwatch
- Start timing -- Click the blue Start button to begin the stopwatch. The display will start counting upward in hours, minutes, seconds, and centiseconds.
- Record a lap -- While the stopwatch is running, click the Lap button to record a split time. Each lap entry shows the individual segment duration and the cumulative total elapsed time.
- Stop the stopwatch -- Click the red Stop button to pause timing. You can click Resume to continue from where you left off.
- Review your laps -- When three or more laps are recorded, the fastest lap is highlighted in green and the slowest in red for quick visual comparison.
- Copy your results -- Click Copy Laps to copy all lap data to your clipboard in a text format ready for pasting into spreadsheets or documents.
- Reset -- Click Reset to clear all data and return the stopwatch to zero, ready for a new session.
How It Works
Under the hood, this stopwatch relies on the browser's performance.now() method, which provides high-resolution timestamps measured from the moment the page loaded. Unlike setInterval-based counters that can drift over time, our approach calculates the true elapsed time on every display update by subtracting the start timestamp from the current timestamp. This means the stopwatch remains accurate even if the browser throttles timers in background tabs or the device briefly slows down.
Lap times are computed by tracking the elapsed time at each lap mark and subtracting the previous lap's timestamp. The fastest and slowest lap detection runs across all recorded laps after each new entry, ensuring the highlighting updates in real time. The entire tool runs client-side in your browser -- no data is sent to any server, and your timing sessions remain completely private.
Frequently Asked Questions
How accurate is this online stopwatch?
Our stopwatch uses the performance.now() API, which provides timestamps accurate to fractions of a millisecond. This is the highest precision available in a web browser, making it suitable for sports timing, lab work, and any activity where precise measurement matters. The display shows centiseconds (hundredths of a second) for readability.
How do I record lap times?
Once the stopwatch is running, click the Lap button to record a split. Each lap shows the time for that individual segment alongside the cumulative total. When you have three or more laps, the fastest lap is highlighted in green and the slowest in red, giving you instant performance feedback.
Does the stopwatch keep running in a background tab?
Yes. The stopwatch calculates elapsed time using absolute timestamps rather than counting intervals, so switching to another browser tab or minimising the window does not affect accuracy. The display catches up immediately when you return to the tab. This makes it reliable for long-running timing sessions.
Can I copy my lap results?
Yes. After recording laps, a Copy Laps button appears below the lap table. Clicking it copies all lap times and cumulative totals to your clipboard in a plain-text format that you can paste into a spreadsheet, training log, or any document for further analysis.
Is there a maximum time the stopwatch can run?
There is no practical limit. The stopwatch will continue running for hours or even days as long as the browser tab remains open. The display format supports hours, minutes, seconds, and centiseconds, so even very long sessions are displayed clearly.
What is the difference between a stopwatch and a timer?
A stopwatch counts upward from zero, measuring how long something takes. A timer counts downward from a set duration and alerts you when it reaches zero. Use a stopwatch when you need to measure elapsed time for an activity, and use a timer when you need to be alerted after a specific period has passed.
