オンラインストップウォッチ

ラップタイム、一時停止/再開、リセット機能付きの無料オンラインストップウォッチ。シンプル、正確、使いやすい。

00:00:00.000

⏱️ Stopwatch Variants

⚡ Simple Stopwatch Minimal, no distractions 🏃 Stopwatch with Laps Unlimited lap tracking 🌐 Online Stopwatch Browser-based, instant ⏱️ Lap Timer For sports & training 🏊 Split Timer Track segment times

About Online Stopwatch

Online Stopwatch is a free, browser-based timing tool that provides precise time measurement with millisecond accuracy. Whether you are tracking workout intervals, measuring cooking times, timing presentations, or conducting science experiments, this stopwatch delivers professional-grade timing functionality. All processing happens entirely in your browser — no data is sent to any server, ensuring complete privacy and instant response times.

Features

  • Millisecond precision — accurate timing down to the thousandth of a second for professional use
  • Unlimited lap times — record as many split times as you need with automatic numbering
  • Pause and resume — stop the timer temporarily without losing elapsed time
  • Keyboard shortcuts — use Space to start/stop, R to reset, and L to record laps for hands-free operation
  • Visual lap display — clear table showing lap number, split time, and cumulative total for each lap
  • Clear laps function — remove all recorded laps with one click while keeping the timer running
  • Responsive design — works seamlessly on desktop, tablet, and mobile devices
  • 100% private — all timing logic runs client-side, no data sent to servers
  • Large display — easy-to-read digital clock format (HH:MM:SS.mmm) visible from a distance
  • Free forever — no usage limits, no ads, no registration required

How to Use

  1. Click the "Start" button to begin timing — the display will start counting up from zero in real-time
  2. Click "Lap" at any moment to record a split time — the lap will appear in the lap times table below
  3. Click "Pause" to temporarily stop the timer — your elapsed time is preserved and you can resume later
  4. Click "Resume" to continue timing from where you paused without losing any elapsed time
  5. Click "Reset" to clear the timer back to zero and remove all recorded laps
  6. Use keyboard shortcuts for convenience: Space (start/pause/resume), R (reset), L (record lap)

Common Use Cases

  • Fitness and sports training — time workout intervals, rest periods, running splits, and circuit training rounds
  • Cooking and baking — track multiple cooking stages, boiling times, and baking durations simultaneously
  • Science experiments — measure reaction times, chemical reaction durations, and physics experiments accurately
  • Presentation and speech practice — time your talks, track segment durations, and improve pacing
  • Gaming and speedrunning — record split times, track personal bests, and analyze performance segments
  • Work and productivity — use the Pomodoro technique, timebox tasks, and measure focused work sessions

Frequently Asked Questions

How accurate is this online stopwatch?

The stopwatch uses your browser's high-resolution timer API for millisecond-level accuracy. It is precise enough for most practical purposes including sports training, cooking, and experiments. For scientific research requiring extreme precision, dedicated hardware may be preferable.

Can I record multiple lap times?

Yes! You can record unlimited laps. Each lap shows the lap number, the split time (time since the last lap), and the cumulative total time. The lap table appears automatically when you record your first lap.

What happens to my laps if I pause the timer?

Your laps are preserved when you pause. The timer simply stops counting until you resume. All previously recorded laps remain visible in the lap table, and you can continue recording new laps after resuming.

Does the stopwatch work if I switch to another tab?

Yes, the stopwatch continues running even if you switch to another browser tab or minimize the window. However, for best accuracy, keep the tab active as some browsers may throttle background tabs.

Can I use keyboard shortcuts instead of clicking buttons?

Yes! Press Space to start, pause, or resume the timer. Press R to reset. Press L to record a lap (only works while the timer is running). These shortcuts make the stopwatch easier to use during activities like workouts.

Is my timing data stored anywhere?

No. All timing data is processed entirely in your browser. No lap times, elapsed times, or any other data are transmitted to or stored on any server. Your privacy is fully protected.

Can I export or share my lap times?

Currently, you can manually copy lap times from the display. For now, the tool focuses on real-time timing. Future updates may include export functionality for lap data.

Does the stopwatch work offline?

Once the page is loaded, the stopwatch will continue to work even if you lose your internet connection, since all processing happens client-side. However, you need an internet connection to initially load the page.

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