Toolkit

Clock Guide

World clock, stopwatch, and countdown timer in one tool.

Back to Clock

What does this tool do

The Clock tool combines a World Clock, Stopwatch, and Countdown Timer in one. World Clock shows live time for any IANA timezone, updated every second. Stopwatch measures elapsed time with lap support using requestAnimationFrame for precision. Countdown accepts hours, minutes, and seconds and counts down to zero with an animated progress ring. All run in your browser—no server.

How to use it

  1. World Clock — Add timezones from the dropdown. View live time and UTC offset. Remove zones as needed.
  2. Stopwatch — Start, stop, resume, lap, and reset. Lap times are recorded in a list.
  3. Countdown — Enter hours (0–99), minutes (0–59), seconds (0–59). Start the timer. At zero, "Time's up!" appears and the ring completes.
  4. Switch tabs — Move between World Clock, Stopwatch, and Countdown.

How it works

World Clock: Uses Intl.DateTimeFormat and a setInterval (1s) to display live time for selected IANA timezones. Reuses helpers from the Timezone Converter. Stopwatch: Uses requestAnimationFrame for drift-free elapsed time; stores lap splits. Countdown: Parses input, drives a countdown with setInterval, and animates an SVG ring. At zero, the timer stops and shows a notification. DST is handled by the browser's Intl API.

All computation runs entirely in your browser. No data is sent to any server.

Use cases & examples

  • Remote meetings — Check time in multiple locations.
  • Workouts — Use the stopwatch and lap for intervals.
  • Cooking — Use the countdown for timers.
  • Focus — Pomodoro-style countdowns.
  • Travel — Compare home and destination time.

Example

  • Add Asia/Ho_Chi_Minh and America/New_York → See both live.
  • Stopwatch: Start, lap at 30s, lap at 60s → Splits recorded.
  • Countdown: 0h 5m 0s → 5-minute timer.

Limitations & known constraints

  • Tab throttling — Background tabs may slow timers; keep tab active for precise countdown/stopwatch.
  • IANA only — Uses IANA timezone names; abbreviations (e.g. EST) may be ambiguous.
  • Countdown range — Hours 0–99, minutes/seconds 0–59.
  • No persistence — Stopwatch and countdown reset on page reload.

All calculations and conversions run entirely in your browser. No data is sent to any server, so your input never leaves your device.