100 Second Timer

About this one hundred second timer

This one hundred-second countdown runs entirely in your browser. Handy for interval training, brief meditations, or short timed games. There is nothing to install, nothing to sign up for, and no data is uploaded when you start, pause, or reset.

How long is 100 seconds? 1 minute and 40 seconds. It is a handy round number for a drill, a plank hold, a sprint interval, or a tea steep — short enough to watch the whole countdown run.

A one hundred-second timer sits just past the minute mark. It is useful for timed drills, short focus bursts, tea steeping, and anything where a strict minute feels slightly too short.

Because this timer is under two minutes, it is ideal for testing the sound setting — start the countdown, let it run, and make sure the end-of-timer tone is audible at the volume you will actually use.

How to use this timer

• Press Start (or the spacebar) to begin the countdown.
• Press Pause (or the spacebar again) to hold the current time.
• Press Reset (or the R key) to return to 100:00.
• When the timer ends, a short tone plays. Click, tap, or press any key to stop it.
• Use the sound toggle to mute the alert — your preference is remembered on this device.

Tips for accurate timing

• Keep this tab visible. Modern browsers slow down background tabs to save power, which can delay the end alert.
• On mobile, keep the screen awake or plug the device in for long sessions.
• For anything safety-critical, use your device's built-in system timer rather than a web page.

Related timers: 1 minute timer, 150 second timer, or 200 second timer.

Looking for a different duration? Browse the TimerZen home page or type any whole-number duration into the URL (for example, /45-minute-timer/, /90-second-timer/, or /2-hour-timer/).

Last reviewed on April 24, 2026.