Precision Online Stopwatch
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00:00.00
Space Start/PauseL LapR Reset
Free Online Stopwatch with Millisecond Precision & Lap Recording
TimerBox's Online Stopwatch provides instant, millisecond-accurate time tracking directly in your web browser. Whether you are timing speed runs, training sprints, measuring classroom speeches, testing software execution, or monitoring athletic intervals, our stopwatch gives you clear split times, automatic fastest/slowest lap detection, and zero-distraction fullscreen view.
Engineered for Precision & Convenience
Millisecond Accuracy
High-frequency delta calculation engine ensures exact timestamp tracking that never drifts, even under heavy multitasking.
Fastest & Slowest Lap Splits
Instantly identifies and highlights your quickest and slowest intervals with color-coded split delta comparisons.
Background Tab Persistence
Keeps timing accurately when you switch browser tabs or minimize your window using wall-clock timestamp offsets.
Fullscreen Focus View
Expand the timer display to fill your monitor or TV screen for group presentations, workouts, and classroom timing.
1-Click Lap Export
Copy formatted lap tables directly to your clipboard for quick pasting into Excel, Google Sheets, or training logs.
Keyboard Hotkeys
Control your sessions effortlessly: Spacebar to Start/Pause, L to record Laps, and R or Esc to Reset.
How to Use the Online Stopwatch
1
Start or Resume Timing: Click the green Start button or press Spacebar on your keyboard. The stopwatch immediately counts up in seconds and hundredths.
2
Record Lap Times & Splits: Click the Lap button or press L while the stopwatch is running. Each lap stores both the individual split delta and the cumulative total.
3
Pause and Review Analysis: Press Pause or Spacebar to freeze the timer. Review color-coded highlights showing your best performance lap and slowest split.
4
Reset or Copy Data: Click Reset or press R to clear the stopwatch and lap history. Click Copy Laps to transfer your recorded split table to your clipboard.
Frequently Asked Questions
Does this online stopwatch keep running accurately if I switch tabs?
Yes. TimerBox computes real-time elapsed duration using high-resolution timestamp deltas (Date.now() / performance.now()). Even when background tab throttling occurs in Chrome, Safari, or Edge, your recorded duration remains 100% pinpoint accurate upon returning.
What is the difference between Lap Time and Total Time?
Total Time represents the cumulative elapsed time from when you first pressed Start. Lap Time (or Split Time) measures the exact duration spent during that specific lap interval alone, helping you track pace variations.
What keyboard shortcuts are supported?
Press Space to Start or Pause, L to record a Lap, R or Esc to Reset, and F to toggle Fullscreen mode.
How are the fastest and slowest laps determined?
When two or more laps are recorded, the system automatically compares all split durations. The shortest split is highlighted in green as your fastest lap, while the longest split is highlighted in amber as your slowest lap.
Is any of my timing data saved or uploaded to a server?
No. All timing measurements and lap recordings are processed entirely client-side in your local web browser. No sign-up is required and your session data remains completely private.
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21 – 40 Minutes