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Stopwatch & Timer

Precision stopwatch with laps, plus countdown and interval timers.

  • 完全無料
  • 登録不要
  • ブラウザ上で安全に動作
00:00.00

Shortcuts: Space start/pause · L lap · R reset

LapLap timeTotal time
ガイド・解説

Three tools in one

This page combines a stopwatch for measuring elapsed time with lap splits, a countdown timer with sound and notifications, and an interval timer for circuit and HIIT workouts. All three display the live time in the browser tab title, so you can switch to another tab or app and still glance at the clock.

Does it keep running in the background?

Yes. The timing is based on real timestamps rather than a counter that ticks only while the tab is visible, so it stays accurate even if you switch tabs, the tab is throttled by the browser, or you lock your screen. When you come back, the displayed time reflects the true elapsed time, which is essential for trustworthy results.

Laps and interval training

The stopwatch's lap feature records split times without stopping the clock, so you can time each segment of a run, a presentation, or a process and export the laps as CSV for later analysis. The interval timer alternates work and rest periods automatically for a set number of rounds, which is exactly what high-intensity interval training (HIIT) and circuit workouts need, with an audio cue at each switch.

Accurate, flexible, and quiet if you need it

Because it uses your device's clock, the stopwatch is accurate to a fraction of a second for everyday timing. Audio alerts can be turned off when you need silence, falling back to a visual or tab-title cue. Whether you are cooking, studying, exercising, or running a meeting, you can pick the mode that fits and keep it visible from anywhere on your screen.

最終更新日: 2026年9月

Frequently Asked Questions

このツールは無料で安全に使えますか?
はい、完全無料でご利用いただけます。ブラウザ内でローカル処理されるため、機密情報も安全です。