Stopwatch & Countdown Timer
Switch between a stopwatch that records laps and a countdown timer with quick presets and a beep when time is up. Timing is based on real timestamps for accuracy.
Runs in your browser. Your files are never uploaded.
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How to use Stopwatch & Countdown Timer
- Open Stopwatch, press Start, and tap Lap to record split times. Pause or Reset any time.
- Open Countdown timer, enter hours, minutes and seconds or tap a preset such as 5 min.
- Keep Play a beep ticked, press Start and leave the tab open.
- Press Test sound once to confirm your volume before relying on the alarm.
Stopwatch versus timer
A stopwatch counts upward from zero and is used to measure how long something takes, such as a run, a presentation or a chemistry reaction. Laps let you record intermediate times without stopping the clock, so you can compare each circuit or each speaker. The lap table lists the time for each lap separately and the running total, and marks the fastest and slowest laps once you have more than one.
A countdown timer works the other way, counting down from a duration you set and signalling when it reaches zero. It suits cooking, workouts, study blocks and meeting agendas.
Why timestamps matter
Computers do not run timers perfectly. If a page is busy or hidden, the code that updates the display may be delayed by tens or hundreds of milliseconds, or by a full second in a background tab. A timer that simply adds a fixed amount on each update would then fall behind. This page records the moment you press Start using a high-resolution monotonic clock, and every refresh subtracts that start from the current moment, so the displayed time is correct whenever it is drawn.
The display refreshes about thirty times a second for the stopwatch and ten times a second for the timer, which is smooth without being wasteful.
Ways to use it
- Use the Pomodoro method with 25-minute focus sessions and short breaks.
- Time exam practice sections or presentations.
- Track interval training with laps.
- Set a tea or egg timer in the kitchen.
- Time how long a meeting item runs to stay on schedule.
Limits
The alarm is a short sequence of beeps and does not repeat. If the browser or device is asleep, it may not play on time. Time is held in memory only, so reloading the page clears running timers and laps.
Why use this stopwatch & countdown timer tool
- Accurate timing. Elapsed time is measured from high-resolution timestamps, not by counting ticks, so it does not drift.
- Lap table. Each lap shows lap time and total, with the fastest and slowest laps marked.
- Presets and alarm. One-tap presets from 1 minute to 1 hour and an audible beep generated in your browser.
- No installation. Works on phones and desktops without an app or account.
Frequently asked questions
Why is the timer more accurate than a simple counter?
Many basic timers add one each time a timer callback fires, and callbacks can be delayed when the tab is busy. This tool stores the start time and calculates elapsed time from the clock on each refresh, so a delayed update never loses time.
Will the alarm sound if I switch tabs?
Usually yes, but browsers may slow down background tabs and, on some phones, suspend them entirely when the screen locks. For critical timing, keep the tab visible and turn up the volume.
Why is there no sound the first time?
Browsers only allow audio after you interact with the page. Pressing Start or Test sound unlocks it. Check that your device is not muted.
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