ストップウォッチ
ラップタイム対応の高精度オンラインストップウォッチ。ブラウザ内で完結します。
使い方
Press Start to begin timing; the same button pauses and resumes. Lap records a split without stopping the clock, and Reset clears everything. Keyboard: Space starts/stops, L records a lap, R resets.
よくある質問
How accurate is this stopwatch?
It measures elapsed time with your browser’s high-resolution monotonic clock (performance.now), so it is accurate to milliseconds and unaffected by system clock changes while running. The display refreshes about 60 times per second.
Does the stopwatch keep running if I switch tabs?
Yes. The elapsed time is computed from timestamps, not from counting screen updates, so returning to the tab always shows the correct total — even if the browser throttled the page in the background.
What do the lap columns mean?
“Lap” is the time since the previous lap press; “Total” is the time since the start. The fastest and slowest laps are marked so you can compare splits at a glance.