How accurate is this online stopwatch?

This stopwatch measures elapsed time using high-resolution browser performance timestamps (Date.now() and performance.now()), delivering sub-10ms precision suitable for workouts, cooking, exams, and speed tests.

Can I record multiple laps?

Yes, you can record unlimited laps. Each lap displays both the cumulative elapsed time and the delta time compared to the previous lap.

Does the stopwatch continue running if I switch tabs?

Yes, because the stopwatch calculates duration based on absolute wall-clock timestamp deltas rather than relying on throttled interval ticks, it maintains perfect accuracy when you switch browser tabs.

Time

Stopwatch & Lap Timer

High-precision digital stopwatch with sub-millisecond tracking, lap splitting, and delta time analysis.

Quick Answer & Summary

An online stopwatch tracks elapsed time with millisecond precision and records split lap intervals. By computing time differences against the system epoch clock, it maintains 100% timing accuracy even when switching browser tabs.

High-Precision Elapsed Time Formula

Elapsed_ms = (Current_Epoch_ms - Start_Epoch_ms) | Lap_Delta = Lap_N_ms - Lap_N-1_ms

Computes delta against high-resolution performance wall clock time.

00:00.00

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Toolbox Editorial TeamVerified Authors

Systems & Security Engineers • Applied Cryptography & High-Performance Web Tools

Updated: August 2026

100% In-BrowserZero server storage

Standards AuditedRFC & ISO compliant

Peer ReviewedEditorial Policy

Documentation & Guide

How to Use Stopwatch & Lap Timer

Start Timer

Click the green 'Start' button or use keyboard controls to initiate high-precision timing.

Record Lap & Split Times

Click the flag button while running to record individual lap durations and cumulative splits.

Review Lap Delta History

Analyze the lap history table showing exact milliseconds and lap-over-lap time deltas.

Pro Tips

Maintains timing accuracy even if backgrounded in another tab

Clear lap history anytime with one click

Practical Examples & Conversions

Input

Press Lap each 400m

Output

Records individual lap pace and total elapsed time

Frequently Asked Questions (PAA)

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Authoritative Standards & Citations

Calculations and algorithms on this page are implemented and verified in strict accordance with the following official technical specifications:

International Organization for Standardization

ISO 8601: Date and Time Formats

Internationally accepted standard for representing dates and times.

Internet Assigned Numbers Authority

IANA Time Zone Database (TZDB)

Authoritative historical and current daylight saving time (DST) database.