How accurate is a one hour countdown?

It does not drift. Each tick works the remaining time out from a real timestamp rather than counting intervals, so a slow frame or a busy machine cannot shave seconds off across sixty minutes. A Web Worker keeps it running while the tab is in the background, which is where a naive browser timer gets throttled and comes back short.

When should the hour start against a parking meter?

From the time printed on the ticket, not from when you got back to your phone. If five minutes have already gone, set fifty-five. It is worth ending a few minutes early as well, because the alarm tells you the hour is up rather than that you are back at the car, and the walk counts against you rather than the meter.

Why use a countdown instead of an alarm at a set time?

A countdown removes the arithmetic. You know the hour started now, but you do not necessarily know off-hand that now plus sixty is 3:47, and a countdown survives being wrong about the current time. If the thing you are working from is a wall-clock moment instead, the alarm clock on this site takes the time itself and rings when the clock reaches it.

1 Hour Timer

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The usual way to get an hour wrong is to start counting from the moment you remembered rather than the moment the hour began. A parking session starts when the ticket is issued, a paper starts when the invigilator says so, a wash started when the door locked. By the time the timer goes on, several minutes have already gone, and a display reading 1:00:00 is quietly telling you something untrue. The fix is unglamorous: subtract whatever has passed before you start, or set fifty-five and take the margin back deliberately instead of discovering later that you never had it.

1 Hour Timer Idle

01:00:00

HH : MM : SS

Hours

Min

Sec

Notify me when it's done

Ends with an audible alarm — keep this tab's sound unmuted. A running countdown keeps counting in a background tab and picks itself back up if you reload.

Open this page with the timer already running → — handy as a bookmark, though your device only lets a page make a sound after you have tapped it at least once.

Why 1 hour

An hour is also the unit almost everything is booked and billed in, which makes it the one duration people time for the record rather than for a reminder. A work block, a lesson, a consultation, a rehearsal: the alarm marks the end of something that gets written down afterwards. That is a fair reason to run it from a page that computes every second from the system clock rather than counting ticks and hoping.

What people set it for

Parking limits and meter windows
A timed exam paper
One billable hour
Slow cooking and braising
A full uninterrupted work block
Laundry and dishwasher cycles

FAQ

How accurate is a one hour countdown?: It does not drift. Each tick works the remaining time out from a real timestamp rather than counting intervals, so a slow frame or a busy machine cannot shave seconds off across sixty minutes. A Web Worker keeps it running while the tab is in the background, which is where a naive browser timer gets throttled and comes back short.
When should the hour start against a parking meter?: From the time printed on the ticket, not from when you got back to your phone. If five minutes have already gone, set fifty-five. It is worth ending a few minutes early as well, because the alarm tells you the hour is up rather than that you are back at the car, and the walk counts against you rather than the meter.
Why use a countdown instead of an alarm at a set time?: A countdown removes the arithmetic. You know the hour started now, but you do not necessarily know off-hand that now plus sixty is 3:47, and a countdown survives being wrong about the current time. If the thing you are working from is a wall-clock moment instead, the alarm clock on this site takes the time itself and rings when the clock reaches it.

1 Hour Timer

Why 1 hour

What people set it for

FAQ

Other preset timers