Online stopwatch

An online stopwatch measures elapsed time after you press Start.

This tool lets you pause a session, resume it, reset it, and record cumulative lap readings in the same tab.

Use it for everyday tasks such as a practice session, a reading activity, or a short comparison.

It is not a certified timing instrument for safety or official competition results.

Start, pause, and resume a stopwatch

Press Start when the event begins.

The large display shows hours, minutes, seconds, and hundredths of a second.

The update rate limits how often you see a new display.

Press Pause when you want to stop accumulating time temporarily. The displayed reading remains in place.

Press Resume to continue from that reading. Press Reset to return to zero and clear recorded laps.

Record any readings you need before resetting or refreshing the page.

Keep the same definition of the timed event throughout a comparison.

Starting after a task has already begun changes what the elapsed total represents.

Record cumulative lap readings

While the stopwatch runs, press Lap to add the current elapsed time to a list.

Each reading is measured from the session’s start, with paused time excluded.

The list stores cumulative readings rather than automatically calculated individual lap durations.

To find a later lap’s duration, subtract the preceding cumulative reading from the next one.

For example, readings of 12 seconds and 25 seconds mean the second interval lasted 13 seconds.

Keep the distinction between a session total and one interval clear.

The tool allows up to 100 lap readings in a session.

Copy or record useful values before you reset the list or leave the page.

How the elapsed time is calculated

The stopwatch uses the browser’s monotonic timing clock while running.

It adds each running interval to the previously accumulated elapsed time when you pause and resume.

It calculates elapsed time from readings of that clock rather than adding one unit for every display refresh.

Display refreshes and the underlying time calculation are separate.

Browser throttling, background tabs, and device sleep can affect updates or the timing environment.

Keep the device awake and the tab available when the reading matters to your task.

The visible hundredths do not promise certified accuracy.

Your timing result depends on the device and browser. It also depends on when you press the controls.

A simple practice-session example

Start the stopwatch at the beginning of a practice task. Press Lap when the first part ends.

Continue timing and press Lap after the next part.

If you pause for a break, press Pause when the break begins and Resume when practice restarts.

The accumulated running time excludes the paused interval.

Record the final cumulative reading when the session ends.

If you also need the total calendar time including the break, record that separately using an appropriate method.

For comparisons across sessions, keep the task, start point, and pause rules consistent.

A longer reading may reflect a different measurement rule rather than a change in performance.

Save useful readings clearly

Write the task name, date, pause rule, and elapsed reading together.

Note whether a listed number is the total or a cumulative lap.

The stopwatch does not save running state through a page refresh.

A refreshed page starts a new timing session, so do not use refresh as a pause control.

If you need a visible period that ends at a chosen duration, use the countdown timer instead.

A stopwatch measures time already elapsed; a countdown shows time remaining.

Check the input before trusting the result

Use a small example you can understand before a longer session.

This helps you confirm the control labels, calculation direction, and way the result is displayed.

Keep a measurement or number beside its unit.

A bare result can be easy to misread later, especially when another tool uses a different unit or comparison basis.

Correct a mistaken input at its source. Recalculate or restart the relevant step, then check the result again.

A neat-looking display does not independently verify the information entered.

Keep a useful record

Write the task name and inputs beside the finished result. Record assumptions that change the result.

Examples include a chosen gap, an electricity rate, or a quoted price.

If you compare two sessions or estimates, use the same measurement rule where possible.

Explain any change in the setup before treating the numbers as a direct comparison.

Keep a copy of source information when it matters to the task.

A supplier drawing, written quote, or clearly stated counting rule makes a result easier to check later.

Browser access and privacy

The interactive controls run in your browser.

JavaScript must be enabled for the calculation or session controls to respond.

No visitor account is required to use the tool.

Calculator inputs are not submitted as a contact message or saved in the site database.

Tools that keep local progress describe that behavior beside their controls.

If a button seems unresponsive, check the input requirements and visible result message first.

Refreshing a timing page starts a new session, so record a useful reading before reloading.

A useful next step

Read the result with the limitations shown beside it.

Use a related guide to check the item or source behind your numbers.

Keep that check separate from the arithmetic. For another task, return to all tools.

Choose a tool that matches your question. Do not change what a result means to fit another task.

Frequently asked questions

How do I start an online stopwatch?

Press Start to begin timing. Press Pause for a break, then Resume to continue the same session.

How do I get the time for each lap?

Displayed laps are total readings from the start.

Subtract the previous reading to find the time between two laps.

Will my stopwatch time stay after I refresh the page?

No. A refresh resets this session and the lap list. Copy useful readings before leaving the page.

Can I use this stopwatch on my phone?

Yes. Keep the page open while timing. Device and browser behavior can affect an everyday timing result.