Calculators & Generators

Countdown Timer (Online Timer with Alarm)

Set a time or tap a preset, then press Start.

By TheCalcTools Updated Formula checked and tested
05:00

A short beep plays when time is up (if your device allows sound).

Countdown Timer (Online Timer with Alarm) by TheCalcTools

How the Countdown Timer (Online Timer with Alarm) works

The timer counts down to a fixed end time, so it stays accurate even if your browser slows down background tabs.

When time is up the display and the tab title change, and a short beep plays. Some phones block sound until you have tapped the page, so keep it open. The 25-minute preset suits the Pomodoro technique.

Worked example

Tap 25 min for a Pomodoro work session: the display shows 25:00 and counts down; take a 5-minute break when it beeps.

Frequently asked questions

Will it alarm if my screen locks?

Phones often suspend web pages when locked. Keep the screen on for important timers.

Sources and further reading

Online Stopwatch (with Laps)Press Start (or the space bar) to time anything, and Lap to record splits Countdown Calculator (Days Until a Date)Pick an event date to see exactly how long is left Time Duration Calculator (Between Two Dates and Times)Enter a start and end date and time to get the duration

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