A stopwatch measures elapsed time from the moment you press start until you press stop. There is no target time and no countdown, just an accurate running clock. StopwatchPro's stopwatch uses your browser's high-resolution timing API, so the numbers you see are accurate to the millisecond rather than rounded to the nearest second like a basic clock app. It works in any modern browser on a phone, tablet or computer, with no download and no account.
A lap time is how long a single segment took, measured from the previous lap press. A split time is the total elapsed time at the moment you press, measured from the start. They describe the same run in two ways.
For example, imagine a four-lap run where you press the lap button at 1:10, 2:25, 3:35 and 4:40 on the clock. Your split times are 1:10, 2:25, 3:35 and 4:40. Your lap times are 1:10, 1:15, 1:10 and 1:05. Reading the laps shows you got faster at the end; reading the splits shows your total progress. Comparing your fastest and slowest laps is a simple way to see whether you are pacing evenly.
The display can show milliseconds, but your own reaction time when pressing start and stop is usually 0.1 to 0.3 seconds, so treat the last digit as a guide rather than a guarantee. For a fair comparison between runs, start and stop at the same point each time. Browsers and phones may refresh background tabs less often to save battery, so keep the tab visible while you time something important. If you need a fixed limit rather than a measurement, use the countdown timer. For turn-based games, try the chess clock.
A stopwatch counts up from zero to measure how much time has passed. A timer counts down from a set duration to zero and alerts you when time is up. Use the stopwatch when you don't know in advance how long something will take.
Yes. Pressing pause freezes the elapsed time exactly where it is; pressing resume continues counting from that point rather than restarting.
Yes — the stopwatch runs in your browser's memory for the current session, so closing or reloading the tab will reset it to zero.
Yes. It is free to use, needs no sign-up or download, and works on phones, tablets and computers.
A lap time is the duration of one segment, measured from the previous lap press. A split time is the total elapsed time from the start at the moment you press the lap button.
It measures time using your browser's high-resolution timer and shows milliseconds. In practice, your own reaction time when pressing the buttons is the biggest source of error.