1 Hour Timer
A 60-minute countdown with an alarm that shows the time left in your browser tab, so you can work in another tab.
1 Hour Timer
1 hour
Ready
Keys: Space start / pause · R reset · + add a minute · F full screen · Esc stop alarm
How it keeps time
- Length: 1 hour = 3,600 seconds.
- On Start: end time = the moment you start + 3,600 s, read from your device’s clock.
- Every update: time left = end time − now, rounded up to the whole second — so it never drifts, even in a background tab.
What an hour is used for
- Food on a hot day. The USDA Food Safety and Inspection Service says perishable food shouldn’t sit out for more than two hours — or more than one hour when it’s above 90 °F, such as at a summer picnic. Start this timer when the food comes out, and refrigerate or discard it when the alarm sounds. At normal room temperature, use the 2 hour timer.
- Kids’ daily activity. The CDC recommends that children and teens aged 6 to 17 get 60 minutes or more of moderate-to-vigorous physical activity every day.
- Exams and practice tests. Put the timer on a projector in full screen so everyone sees the same time, and the digits are readable from the back of the room.
- Meetings and deep work, where the countdown in the browser tab keeps the time visible while you use other tabs.
How the display handles hours
The timer shows hours, minutes and seconds — 1:00:00 at the start — and switches to minutes and seconds (59:59) once less than an hour is left. It counts from the end time you set when you pressed Start, not by adding up seconds, so it stays exact over the full hour even if your browser slows the page down in a background tab. If your computer goes to sleep, the browser may pause the page; the countdown is still correct when it wakes, and the alarm sounds then if the time has passed.
How this timer works
Press Start, tap the digits or press Space. The timer saves the end time on your device’s clock and shows end time − now, rounded up to the second, so it stays exact even when your browser slows down background tabs; the remaining time also shows in the tab’s title. The alarm is scheduled on the Web Audio clock for the end time and beeps for up to a minute (phones that support it also vibrate). While the timer runs, the page asks the browser to keep the screen on. Nothing is sent anywhere: the timer runs entirely in your browser.
Other timers
Shorter: 45 Minute Timer. Longer: 2 Hour Timer. For any other length, use the countdown timer; to time how long something takes, use the stopwatch. Counting down to a date instead? See the holiday countdowns.
Frequently asked questions
How long can food sit out on a hot day?
No more than one hour when the temperature is above 90 °F, and no more than two hours otherwise, according to the USDA Food Safety and Inspection Service.
How much exercise do kids need each day?
The CDC recommends 60 minutes or more of moderate-to-vigorous physical activity every day for children and adolescents aged 6 to 17.
Can I see the time left without switching back to this tab?
Yes. While the timer runs, the remaining time appears in the browser tab’s title, for example “42:10 · 1 Hour Timer”.