Is this stopwatch accurate?

Yes. The stopwatch uses requestAnimationFrame and Date.now() for high-resolution timing, accurate to within a few milliseconds in typical browser environments. For scientific or legal timing you need dedicated hardware, but for everyday use — workouts, cooking, races, studying — this is more than sufficient.

How many laps can I record?

There is no hard limit. The lap list is held in browser memory for the current session and renders smoothly even with hundreds of laps. Best and worst lap times are highlighted automatically as laps are added.

Does the stopwatch keep running if I switch tabs?

Yes. The timer tracks elapsed time using wall-clock timestamps (Date.now()), not a frame counter. Even if the browser throttles the animation when you switch tabs, the displayed time catches up correctly when you return — no time is lost.

What do the green and red lap times mean?

Green marks your fastest lap (best time) and red marks your slowest lap (worst time). These highlights only appear when you have two or more laps recorded, so there is always a meaningful comparison.

Can I use this stopwatch on mobile?

Yes — the stopwatch is fully responsive and works on any modern mobile browser. The large display is easy to read at a glance, and the buttons are sized for comfortable touch input.

ストップウォッチ

ラップ記録機能付きの精密ストップウォッチです。開始・停止・ラップ記録が可能で、最速・最遅ラップタイムが自動でハイライト表示されます。

00:00.00

MM:SS.cs

使い方

ラップ記録機能付きの精密ストップウォッチです。開始・停止・ラップ記録が可能で、最速・最遅ラップタイムが自動でハイライト表示されます。

1Click 'Start' to begin timing. The display updates in real time showing minutes, seconds, and centiseconds.
2Click 'Lap' at any point to record a split time. The lap table shows each lap's individual time and cumulative total.
3Click 'Stop' to pause the timer. Click 'Resume' to continue from where you left off.
4Watch for green (fastest lap) and red (slowest lap) highlights — they update automatically as you add more laps.
5Click 'Reset' to clear everything and start fresh. The average, best, and worst lap stats appear below the lap list.

主な機能

High-resolution timing using Date.now() timestamps — accurate even when you switch browser tabs
Unlimited lap recording with automatic best (green) and worst (red) lap highlighting
Live stats panel showing average, best, and worst lap times (appears after 2+ laps)
Start / Stop / Resume / Reset controls with a clean dark display for easy reading
Fully responsive — works on desktop and mobile browsers without any installation

よくある質問

詳しく読む

Online Stopwatch with Lap Timer — How to Time Anything Right in Your Browser