Pre-quartz timing
Mechanical stopwatches could be accurate to 1/10th of a second—good enough to time early Olympics before quartz took over.
History
Online Stopwatch with Lap Timer, Splits & Fullscreen
Free Online Stopwatch with Laps & Splits
00:00:00.000
More options: Export & settings
Export and share
Automatically saves elapsed time and lap history in this browser. Clear saved session anytime.
Quick presets
Sound, alert, and screen
Display and shortcuts
Shortcuts: Space Start/Pause • L Lap • R Reset • F Fullscreen
Laps (0)
Fastest Lap
--
Slowest Lap
--
Average Lap
--
| # | Timestamp | Split (Total) | Lap Δ | Actions |
|---|---|---|---|---|
| No laps yet. | ||||
Preset: Manual mode
Advertisement
About this Stopwatch
Release Updates
- Simplified the first-screen controls to Start/Pause, Lap, Reset, Fullscreen, and an expandable options panel.
- Added local session autosave, clear saved session, and shareable stopwatch links with elapsed time and laps.
- Added sound options, keep-screen-awake support, and optional target time alerts.
- Added lap rename, delete, clear-laps-only, oldest/newest sorting, Excel export, and copy summary.
- Added quick presets: Workout, Study Sprint, and Race Splits.
- Added lap analytics (fastest, slowest, average) with personal-best row highlight and pace delta coloring.
- Added display toggles for milliseconds, compact mode, and high-contrast mode.
- Improved keyboard safety with shortcuts toggle, menu-aware shortcuts, and optional reset confirmation on R.
- Improved fullscreen UX with auto-hiding controls that reappear on activity.
- Added JSON export/import and Copy Markdown export for notes/docs workflows.
How to use the online stopwatch
Click Start or press Space to begin timing. Use Lap or L to capture a lap, Reset or R to clear the stopwatch, and F for fullscreen. The stopwatch starts as a simple count-up timer, with advanced exports and display settings tucked into Export & settings.
Online stopwatch with lap times
Each lap records a UTC timestamp, total split time, and lap delta. Rename laps for easier notes, delete mistakes, sort oldest or newest first, and clear laps without resetting the elapsed stopwatch time.
Stopwatch for workouts and race splits
Use the workout and race presets to label laps as sets or splits. Fastest, slowest, and average lap analytics update automatically, with the fastest row highlighted and lap deltas colored against your average pace.
Stopwatch for classrooms, meetings, and presentations
Fullscreen mode keeps the clock visible across a room. Optional sound on start/stop or lap can make timing changes easier to notice, while the keep-awake setting helps prevent the screen from dimming during longer sessions.
Stopwatch for experiments and productivity sprints
The browser’s high-resolution clock (performance.now()) keeps elapsed timing stable even if the system
clock changes. Optional target alerts can notify you at 5 minutes, 10 minutes, or a custom minute mark without turning
the stopwatch into a countdown timer.
Export lap times to CSV, Excel, Markdown, or JSON
Copy a quick summary, copy a tab-separated lap table, export CSV for spreadsheets, download an Excel-compatible file, copy Markdown for notes, or save/import a JSON session. You can also copy a shareable link with the current elapsed time and lap history.
Privacy-first browser stopwatch
Timing, lap history, settings, and autosave all stay in this browser using local storage. Nothing is uploaded while the stopwatch runs. Clear the saved session anytime from the settings panel.
Stopwatch: FAQs
How accurate is this stopwatch?
It uses performance.now() for high-resolution timing and is not affected by manual system-clock changes while running.
Do you store or upload my lap data?
No. All operations happen locally in your browser. You decide if you copy or export laps.
What keyboard shortcuts can I use?
Space to Start/Pause, L to Lap, and R to Reset.
Does it keep timing if the tab is inactive?
Yes. Elapsed time is computed from a monotonic clock when rendering resumes, so pausing the tab doesn’t lose accuracy.
Advertisement
5 Fun Facts about Stopwatches
Reaction time bias
Human start/stop reactions add about 0.15–0.25 s each—why automated timing transformed sprint records.
Human limits
World’s tiniest stopwatch
Atomic clocks can resolve time to quadrillionths of a second—a cosmic leap from handheld lap buttons.
Precision
Lap ≠ split
A lap is the time between presses; a split is the cumulative total. Pro timers show both so pacing adjustments are easy.
Timing lingo
Marathon timing tolerance
Major marathons accept results within ±1 second on gun time, but chip timing gives personal precision down to 0.1 s.
Race rules
00:00:00.000
Lap times
| # | Split | Lap |
|---|