What is a Stopwatch?
A stopwatch measures elapsed time from when you start to when you stop. This display shows hundredths of a second (0.01 s), while calculations use millisecond timestamps. Display resolution does not guarantee the same measurement accuracy. A timer counts down; a stopwatch counts up.
- Start: Begin time measurement
- Pause: Temporarily stop measurement
- Resume: Continue from where you paused
- Reset: Return time to zero and clear lap records
- Lap: Record current time while continuing
How to Use the Stopwatch
Getting Started
Press 'Start' to begin measuring elapsed time. The display uses minutes:seconds.hundredths: 01:23.45 means 1 minute, 23 seconds and 45 hundredths. An hours field appears after one hour.
Recording Laps
Press 'Lap' while running to record split times. Useful for comparing different segments.
Pause & Resume
Use 'Pause' to stop and 'Resume' to continue measuring from where you left off.
Managing Records
Laps and stopwatch state are saved automatically when browser storage is available. 'Export Excel' downloads a CSV file you can open in Excel or a spreadsheet. You can delete individual laps; 'Reset' clears both elapsed time and lap records.
Stopwatch Use Cases
Study & Focus
Track study time with Pomodoro technique (25 min work + 5 min break) or measure total daily study hours.
Sports & Fitness
Record workout times and lap splits for running, swimming, cycling. Perfect for interval training.
Game Speedruns
Measure game completion times and compare segment records. Challenge your personal best.
Cooking Timing
Perfect for precise cooking times - boiling pasta, grilling steaks, and more.
Work Productivity
Measure time spent on tasks to analyze and improve work efficiency.
Test & Competition Prep
Practice solving problems within time limits or rehearse presentations.
Frequently Asked Questions
What's the difference between a stopwatch and a timer?
A stopwatch starts from zero and measures elapsed time indefinitely, while a timer counts down from a set time to zero. Use a stopwatch for 'how long did it take' and a timer for 'how much time is left'.
Will my records be saved if I close the browser?
When browser storage is available, laps, elapsed time and running or paused state are saved locally. Reopening a running stopwatch adds time since its last saved checkpoint using the device clock; a paused stopwatch stays paused. Device-clock changes while the page is closed can affect restored elapsed time. Clearing site data removes saved records.
Can I use other apps while the stopwatch is running?
You can switch apps while keeping the tab open, but display updates may pause in the background. Elapsed-time behavior during screen lock or device sleep can vary by browser and operating system, so check the reading when you return. If you close the tab, reopening restores the running or paused state saved in browser storage.
What's the maximum measurement time?
The app does not impose a measurement-duration limit. Below one hour, the display uses minutes:seconds.hundredths; from one hour, it uses hours:minutes:seconds.hundredths. More display digits do not guarantee greater measurement accuracy.
Can I save lap records?
Choose Download CSV to save lap records as a CSV file. It can be opened in Excel or Google Sheets; it is not an .xlsx workbook.
Display Resolution and Timing Accuracy
While this page is open, elapsed time comes from performance.now(), a monotonic clock unaffected by changes to the device's date and time. Laps and pauses use the timestamp when the browser handles the action, rather than the previous displayed frame.
Browser privacy settings, input processing, rendering and device load can affect resolution or delay. Screen-lock and sleep behavior also varies across browsers. After reopening a closed page, saved running time is restored using the device clock. Use this stopwatch for everyday timing; official event records require validated timing equipment.
Recording Activity Splits by Hand
A hundredths-of-a-second display does not verify manual taps or device and browser timing to that accuracy. Use the relevant organization's equipment and procedures for official results or health and fitness assessments.
Lap Timing Guide by Activity
These are examples of dividing an activity with manual Lap presses. They do not prescribe distance or exercise intensity, and the stopwatch cannot detect movement automatically.
| Activity | Lap Unit | Key Usage Point |
|---|---|---|
| Running Intervals | 400m / 1km | Check pacing consistency and detect late-stage drop-off |
| Swimming Splits | 25m / 50m / 100m | An observer presses at the same wall touch to record splits and totals |
| Cycling | 1km / 5km | Compare route sections pressed at safe stopping points |
| Hiking | Trail segments | Track pace between rest points, summit, and descent |
| Repeated movement | Chosen segment end | Record elapsed time for the same movement |
| Music Practice | Movement / measure | Time difficult passages, measure full performance length |
| Presentation Rehearsal | Per slide | Adjust content density, predict total runtime |
| Course practice | Chosen segment end | Note segment times separately from official scoring |
| Game Speedrun | Checkpoint | Compare each segment to personal best, target loss zones |
| Cooking Steps | Sauce / cook / plate | Optimize parallel tasks, build timelines for guests |
Agree on start and lap markers before measuring and compare similar conditions. Laps are saved when browser storage is available, but an active run does not continue after the tab closes. Export important records as CSV.
Privacy Notice
Your tool settings and records are stored in this browser, not uploaded as tool data. Other people using the same browser may be able to access them. For analytics and advertising details, see the Privacy Policy.