Chronometer & Lap Timer
A precise stopwatch with laps, splits and a countdown mode. Space starts, L laps, R resets — and it keeps counting if you reload.
Space start / pause · L lap · R reset · F fullscreen
| # | Lap | Split | Δ best |
|---|
How to Use Chronometer & Lap Timer in 3 Steps
Start
Press Start or hit Space. The clock is timestamp-based, so it stays accurate in background tabs and even survives a page reload.
Lap
Press Lap or L at each checkpoint. Every row shows the lap time, the running split and the gap to your best lap; fastest and slowest are highlighted and the stats update live.
Export or count down
Copy the laps as text or download them as CSV. Switch to Countdown, type a duration or tap a preset, and a chime plays when it reaches zero. F goes fullscreen for a wall display.
Chronometer & Lap Timer — Frequently Asked Questions
How accurate is it?
Each tick is computed from the system clock (Date.now()) rather than by counting intervals, so drift is zero — the display is only ever as late as the frame it is painted in (≈16 ms) and the stored lap times are exact to the millisecond.
Does it keep running if I close the tab?
Yes. The start timestamp and laps are saved in your browser’s local storage, so reopening the page shows the correct elapsed time. Clearing site data resets it.
Can I use it on a phone?
Yes — the controls are large touch targets and the display scales to the screen. Add the page to your home screen for a one-tap stopwatch. Note that mobile browsers pause JavaScript in background tabs, but because the clock is timestamp-based the time is still right when you return.
What does “Δ best” mean?
The difference between that lap and your fastest lap so far, so you can see at a glance how consistent your intervals are. The average, best and worst lap appear above the table.
Does the countdown chime need permission?
No — it uses the Web Audio API, which only needs you to have interacted with the page (pressing Start counts). Turn the chime off in Settings if you prefer silence.
Is my input sent anywhere?
No. Everything is computed by JavaScript in your browser tab. Nothing is uploaded, logged or stored by Toolity.