When to use a countdown timer
Count down to a date, a holiday, or a short duration, and how that differs from asking what time it will be.
Countdown
You already know the target
A countdown is for a moment on the calendar: New Year, a launch, a train. You set the target once and watch days, hours, minutes, and seconds fall. That is the opposite of an offset page, where the target moves every time “now” moves.
Holiday pages on this site pick the next occurrence of that date in your local year. After the day passes, they roll to next year so the countdown stays meaningful.
Short duration countdowns
5 minutes, 10 minutes, 25 minutes, 1 hour: these are focus or break timers. The page turns the duration into a target by adding it to the current time, then counts down. Refreshing a duration URL builds a new target from the new now, so it is a fresh timer, not a paused one.
Do not use a countdown to reconstruct the past
Countdowns expire at zero. They do not answer “what time was it”. If the event already happened, use an ago offset or the difference calculator with the historical datetime.
Questions
Does the countdown run if I close the tab?
The remaining time is always “target minus now”. Open the same holiday URL later and it continues from the current clock. A custom datetime you typed without a URL may not survive a refresh unless it is still in the field.