A one hour timer is the standard unit for almost everything scheduled: meetings, lessons, gym sessions, billing increments, parking, and slow cooking steps. It is also the interval most people use when they want to bound a session without the granularity of minutes, saying an hour on this and then stopping. The page opens with sixty minutes already loaded, so there is nothing to set. The countdown is derived from a fixed end time rather than counting ticks, which keeps it accurate over the full hour and through background tab throttling, and it alerts you when it reaches zero. Over an interval this long, drift in a naive tick-counting timer is easily tens of seconds, which is the main reason this approach matters. Sixty minutes and one hour are the same interval, so this page covers both. For a longer run see 2 Hour Timer, and for a shorter block see 45 Minute Timer.
Countdown Timer is a flexible tool that covers both short-duration timers measured in minutes and seconds and long-duration countdowns to calendar dates measured in days, hours, minutes, and seconds. Short-duration timers are the more common daily use case: a 20-minute timer for a Pomodoro work session, a 7-minute timer for a rest between sets, a 12-minute timer for cooking pasta. Long-duration countdowns are used for event planning and motivation: a website launch date, a product release, an exam or presentation deadline, or a personal milestone. The audio alert at zero ensures the timer is useful even when the browser tab is not visible, such as when cooking or exercising and the screen is not being watched. For structured interval-based work, Pomodoro Timer provides an automated version that cycles through work and break periods without requiring manual resets, which is more convenient than manually setting a countdown timer for each session. Countdown Timer is more flexible for one-off or non-standard durations. The timer uses the browser's requestAnimationFrame loop for the display update and tracks elapsed time using the high-resolution performance.now() API, which provides accuracy that is not affected by the system clock being adjusted during the countdown. The tool works reliably when the browser tab is in the background on desktop browsers, though mobile browsers may throttle background JavaScript execution to reduce battery drain. The tool runs free in the browser without installation.