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 & Timer — Laps, Splits, Fullscreen, CSV
Free Online Stopwatch with Laps & Splits
00:00:00.000
Shortcuts: Space Start/Pause • L Lap • R Reset • F Fullscreen
Laps (0)
| # | Timestamp | Split (Total) | Lap Δ |
|---|---|---|---|
| No laps yet. | |||
About this Stopwatch
This free online stopwatch delivers precise timing with zero data collection. It uses the browser’s high-resolution
clock (performance.now()) so elapsed time remains accurate and smooth, even if your computer’s system
time changes while the timer is running. Everything operates client-side—start, pause, laps, and exports—so your lap
data never leaves your device unless you choose to copy or download it.
Core controls are intentionally simple: click Start (or press Space) to begin timing, use
Lap (or L) to capture a lap with both the cumulative split and the delta since the previous lap,
and press Reset (or R) to clear the session. Go fullscreen with F to keep the display
front-and-center. The lap table shows lap #, UTC timestamp, split (total), and lap delta formatted as
hh:mm:ss.mmm. When you’re done, export CSV for spreadsheets or copy a tab-separated version to paste into
notes, reports, or project trackers.
Typical use cases include interval training, productivity sprints (e.g., Pomodoro-style sessions without a countdown), classroom or lab timing, user-research tasks, speed-runs, or any workflow where you need quick, trustworthy lap capture. Because this stopwatch avoids network requests and uploads, it’s suitable for privacy-sensitive contexts and low-connectivity environments.
For accessibility and comfort, the display uses tabular numerals to eliminate layout shifts as digits change, and keyboard shortcuts minimize pointer use. If you need calendar math alongside timing, try our related tools below for date differences, time-since/until, and timestamp conversions. Together they form a lightweight, privacy-preserving time toolkit.
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.
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