15 Second Timer
A ready-to-go 00:15 countdown -- press Start, or set a different duration below if you need one.
Keyboard: Space start/pause, R reset, Esc stop alarm.
What a 15 second timer is used for
- the original maximum length of a single Instagram Story segment when the format launched
- a classic 15-second television commercial slot, standard alongside the 30-second spot
- a fast between-set breather at the gym
- a quick "one more thing" addition to a pitch
- a short palate-cleanser pause
Why 15 seconds
Fifteen seconds is a real broadcast-advertising unit, not just a round number -- the 15-second commercial has been a standard, cheaper alternative to the 30-second spot for decades, and short-form social video formats borrowed the same length when they first defined a single segment's maximum duration.
15 seconds = 0.25 minutes = 1/240 hour
How it stays accurate
Like every timer on this site, this one never counts down by subtracting one second at a time -- it records the exact target end timestamp the moment you press Start, then recomputes the time left from that fixed target on every screen update. Switching tabs, minimizing the window, or letting the browser throttle a background tab doesn't cost any accuracy, because the next update still does the subtraction fresh rather than trying to catch up on missed ticks. The alarm itself is synthesized with the Web Audio API -- no audio file, nothing an ad blocker could interfere with -- and repeats until you stop it with the Escape key, the Stop alarm button, or by starting a new countdown.
Frequently Asked Questions
What is a 15 second timer good for?
A few common uses: the original maximum length of a single Instagram Story segment when the format launched; a classic 15-second television commercial slot, standard alongside the 30-second spot; a fast between-set breather at the gym.
How long is 15 seconds in other units?
15 seconds = 0.25 minutes = 1/240 hour.
Does this 15 second timer stay accurate if I switch tabs?
Yes -- it stores the exact moment the countdown should end and recomputes the time left from that fixed target on every update, rather than counting ticks, so a background tab that gets throttled for a while doesn't cost any accuracy.
Why is 15 seconds a notable duration?
Fifteen seconds is a real broadcast-advertising unit, not just a round number -- the 15-second commercial has been a standard, cheaper alternative to the 30-second spot for decades, and short-form social video formats borrowed the same length when they first defined a single segment's maximum duration.