12 Hour Timer
A free 12 hour timer that opens preset to 12 hours. Press Start and it counts down in your browser, sounding an alarm at zero. Great for long focus blocks, slow cooking, study sessions and naps. No download, no signup.
What is this timer good for?
- A long focus or writing block with scheduled breaks
- Slow cooking, braising or smoking food
- Tracking a parking meter or appointment window
- A movie-length rest, nap or quiet period
- Capping screen time or a gaming session for kids
How to use it
- The timer opens preset to 12 hours.
- Adjust the hours, minutes or seconds for a different length.
- Press Start and the big display counts down.
- An alarm sounds at 00:00:00 — press Reset to run it again.
How long is 12 hours?
720 minutes is exactly 12 hours — 43,200 seconds in total. That is roughly 50.0% of a 24-hour day. Half of 12 hours is 6 hours, and two rounds back to back add up to 24 hours.
Twelve hours is exactly half a day — one full sweep of the clock face.
Things that take about 12 hours
- Track a 12-hour charge, soak, cure or defrost without watching the clock.
- Time a 12-hour road-trip leg or long-haul study day with a proper break at the end.
- Limit a weekend gaming or streaming marathon to 12 hours.
- Cap a 12-hour work shift, freelance block or hackathon sprint with a hard stop.
FAQ
Will it ring if I switch tabs?
Yes. The timer calibrates against your system clock, so it stays accurate even in a background tab. Just don't close the tab.
Do I need to download anything?
No. The timer runs entirely in your browser with no download, signup or plugin.
Can I change the duration?
Yes. Type any hours, minutes and seconds into the fields, or pick a related timer above.
Is it free?
Yes, it is completely free to use.
How many minutes are in 12 hours?
12 hours is 720 minutes, or 43,200 seconds (12 × 60 × 60).
Does a 12 hour countdown stay accurate for that long?
Yes. The countdown is anchored to your device's clock rather than counting ticks, so even across the full 12 hours it stays accurate to the second.
What if I need a bit more or less than 12 hours?
Adjust the hours, minutes and seconds fields before pressing Start — the 12-hour preset is only a starting point, and the Related links above jump to neighbouring lengths.