Two Tools That Count in Opposite Directions
A timer counts down from a duration you set and tells you when it runs out; a stopwatch counts up from zero and tells you how long something took. They sound interchangeable and are not: one is for enforcing a limit, the other for measuring a span you do not know in advance.
This page provides both, along with lap timing for splitting a single run into segments.
How to Use the Timer and Stopwatch
Pick the mode by what you are trying to find out, not by which one you used last.
- Choose the timer when you know the duration in advance, cooking, a timed exercise, a meeting segment, a study block.
- Set the duration and start it. The countdown runs from the clock, so switching tabs or locking the screen does not pause it.
- Choose the stopwatch when you want to measure something whose length you do not know, such as how long a task actually takes.
- Use laps to split one continuous run into segments. Each lap records the split without stopping the overall count.
- Reset between separate measurements rather than carrying a running total, unless the total is what you are after.
Why Browser Timers Drift, and What Prevents It
A naive timer adds up intervals, sixty ticks of one second makes a minute, and loses time whenever the browser is busy or the tab is in the background, where timer callbacks are deliberately throttled. Over an hour that approach can drift by minutes, which is exactly when you notice.
The reliable approach is to record the start time and compare it against the current clock on every update. Then the display is derived from real elapsed time rather than accumulated, and a tab that was throttled for two minutes shows the correct value as soon as it wakes. That is how this one works, so leaving the tab in the background is safe.
Timer or Stopwatch?
The distinction is about whether the duration is known before you start.
| Situation | Use | Why |
|---|---|---|
| Boiling an egg for 7 minutes | Timer | The duration is fixed in advance |
| Finding out how long a task takes | Stopwatch | The duration is the unknown |
| A 25-minute focus block | Timer | The limit is the point |
| Timing laps of a run | Stopwatch with laps | Splits within one continuous span |
| A three-minute presentation | Timer | You need warning before the limit |
| Recording how long a meeting ran | Stopwatch | Measuring after the fact |
For repeated work-and-rest intervals, exercise sets, or focused work blocks, a dedicated interval tool handles the cycling for you rather than requiring a reset each round.
Background Tabs, Sound and Accuracy
Because the count is clock-based, the elapsed time stays correct in a background tab. What browsers do restrict is the alert: a tab that has never been interacted with may not be allowed to play sound, and a phone with the screen off may delay a notification. If a timer must be heard, keep the tab in the foreground or use a device alarm as a backup.
For casual use the accuracy here is more than sufficient, since display updates land within a few tens of milliseconds. For anything where a hundredth of a second decides an outcome, official race timing, laboratory measurement, purpose-built equipment exists precisely because a browser makes no timing guarantees.