Stopwatch & Countdown

Track time with precision using our stopwatch with lap functionality, or set a countdown timer for productivity and fitness.

Stopwatch with Microsecond Accuracy & Timer

00:00:00
.000
Lap Time
Hours
Minutes
Seconds
05:00

🔧 Related Tools

Common Use Cases & Examples

🏃 Training
Intervals, splits, rest timers
laps
🍳 Cooking
Multiple countdowns for recipes
alerts
⏳ Pomodoro
25/5 focus cycles
auto-repeat
🧪 Experiments
Accurate timing & logging
monotonic
⏱ Prefer monotonic time
Compute elapsed time from performance.now() deltas, not Date.now().
🧭 Avoid interval drift
Use requestAnimationFrame (or a tight setInterval) but derive display from accumulated elapsed.
🔔 Graceful alerts
Fallback to vibration if audio blocked; show a banner via the Notifications API when permitted.
🔒 Battery & privacy
No telemetry. Alerts only after explicit user interaction/permission.
🧩 Technical Implementation
Time formatting

⏱ Stopwatch & Countdown Basics

  • Stopwatch: start • pause • resume • reset • laps
  • Countdown: set duration • start • pause • resume • reset
  • Alarms: optional sound, vibration, and desktop notifications
  • Precision: high-resolution timing with performance.now()
  • Runs entirely in your browser — no data leaves your device.

📊 Modes

  • Stopwatch: counts up from 00:00:00.000
  • Countdown: counts down from a target (e.g., 25:00) to 00:00
  • Auto-lap: optional lap every N seconds/minutes

🖥 Display & Formatting

  • Formats: hh:mm:ss.mmm or mm:ss for short timers
  • Leading zeros for readability
  • Lap table with split and delta times

🎯 Accuracy & Drift

  • Uses monotonic clock (performance.now()) to avoid system clock changes
  • Renders with requestAnimationFrame but computes time from deltas (no setInterval drift)
  • Accurate stopwatch and countdown with start/pause/reset and a beep at zero. Runs locally in your browser.

⚙️ How to Use

  1. Select Stopwatch or Countdown mode.
  2. For Stopwatch: press Start, use Lap, Pause/Resume, then Reset.
  3. For Countdown: set time, press Start. Optionally enable Sound, Vibrate, or Notify.
  4. Keep the tab open — background tabs still track time accurately.

⌨️ Keyboard Shortcuts

  • Space Start/Pause • L Lap • R Reset
  • Countdown: ↑/↓ adjust field • Enter Start/Pause

💡 Tips

  • Enable “Keep screen awake” on mobile (if supported) for workouts.
  • Allow notifications to get alerts when the countdown ends in background.
  • Export laps as CSV if you need logs.

Stopwatch & Timer – Frequently Asked Questions

Click Start to begin, Pause to pause, and Reset to clear the time. You can also use the keyboard: Space toggles Start/Pause and R resets.

Enter your desired minutes and seconds, then click Start Countdown (or press Enter). A beep will sound when the timer reaches zero.

Yes. The stopwatch and countdown use precise system time to ensure accuracy, even if the browser tab is throttled or inactive.

Most browsers block audio until you interact with the page. Click anywhere or press a button to enable sound. Also check your volume and device’s Silent mode.

No. Everything runs locally in your browser. Nothing is uploaded or stored on a server.