How accurate is an online stopwatch?

Online stopwatches using JavaScript can achieve accuracy of 10-16 milliseconds, which is sufficient for most practical uses like sports timing, workouts, and general time measurement.

Does the stopwatch work offline?

Yes, once the page is loaded, the stopwatch runs entirely in your browser and works without an internet connection.

Can I record multiple lap times?

Yes, you can record unlimited lap times. The stopwatch shows both split times (duration of each lap) and cumulative total time, with best and worst laps highlighted.

100% private · no tracking · works offline100% client-side/no data leaves your browser/no accounts/works offline

The Syntax Diaries

Blog Tools Tutorials About

build log live

The Syntax Diaries

Practical code notes, tools & guided learning for developers.

Blog Tools Tutorials About Contact

Privacy Terms Cookies Admin

100% private · no tracking · works offline100% client-side/no data leaves your browser/no accounts/works offline

The Syntax Diaries

Blog Tools Tutorials About

build log live

Online Stopwatch | The Syntax Diaries

Back to toolsProductivity

Online Stopwatch

Free stopwatch with lap times and countdown timer. Millisecond precision.

00:00.00

Why Use Our Online Stopwatch?

Millisecond Precision

Accurate timing down to 10 milliseconds. Perfect for sports, workouts, and experiments.

Lap Times

Record unlimited laps with split times. Highlights your best and worst laps.

Countdown Mode

Set a custom countdown timer with audio alert when time's up.

Related Tools

Browse all →

Productivity

Pomodoro Timer

Focus timer for productivity with work/break intervals.

Open tool →

Productivity

Event Countdown Creator

Create countdown timers for birthdays, anniversaries, and events.

Open tool →

Accessibility

Color Contrast Checker

Check WCAG contrast ratio between two colors.

Open tool →

Accessibility

Keyboard Navigation Test

Test accessibility using keyboard-only input.

Open tool →

Accessibility

Image Accessibility Checker

Verify if images have proper alt text.

Open tool →

Analyzer

Free Online Text Comparison Tool

Online Text Diff Checker – Compare Text, JSON, CSS Side-by-Side

Open tool →

Works Everywhere

Responsive design works on desktop, tablet, and mobile devices.

No Download

Works directly in your browser. No app installation needed.

100% Free

No registration, no ads, no limits. Use as many times as you need.

Common Uses for Stopwatch

Sports & Fitness

Timing running laps or sprints
HIIT workout intervals
Swimming lap times
Rest periods between sets

Work & Study

Timing presentations or speeches
Exam practice sessions
Meeting time management
Task duration tracking

Frequently Asked Questions

How accurate is the stopwatch?▼

Our stopwatch uses high-resolution timing with JavaScript's Date.now() and updates every 10 milliseconds. While browser-based timers can't match dedicated hardware, it's accurate enough for most practical uses like sports, workouts, and general timing.

What are lap times and split times?▼

A lap time (or split time) is the duration between two consecutive lap markers. The total time is cumulative from when you started. For example, if you complete lap 1 in 30 seconds and lap 2 in 25 seconds, your split for lap 2 is 25s and total is 55s.

Does it work if I switch browser tabs?▼

Yes! The timer continues running even when you switch tabs. The current time also shows in the browser tab title so you can monitor it without coming back to the page.

Can I use this on my phone?▼

Absolutely! The stopwatch is fully responsive and works on any device with a web browser - smartphones, tablets, laptops, and desktops. Just open the page and start timing.

What's the difference between stopwatch and countdown?▼

A stopwatch counts up from zero to measure elapsed time. A countdown timer starts from a set time and counts down to zero, alerting you when time's up. Use stopwatch for measuring durations, countdown for setting limits.