45 Minute Countdown — Free Online Tool

What this one is for

Lesson and lecture length
Project it on the board
Half-time alarm if you split it

The lesson and lecture length, counted down where a whole room can see it. Useful for splitting a session cleanly at the halfway mark. It opens at 45:00; change that with the chips under the dial.

Worth knowing

The length of a lesson, a lecture or a properly run meeting.
Leaves changeover time inside the hour, which is why timetables use it.
Near the practical ceiling of sustained attention for a full room.

Getting the most from the 45 minute countdown

Put it where the room can see itFull screen with F, or share the tab in a call. Everyone working to the same visible number removes the awkwardness.
Say what happens at zeroA countdown without a stated consequence is decoration. Announce it before you start.
Extend it openly if you mustThe plus one minute button adds time without resetting, so the room can see exactly what changed.

Related timers

Questions people ask

Why are lessons 45 minutes long?

It is a scheduling convention that leaves changeover time inside an hour, and it sits near the practical ceiling of sustained attention for most classes.

Can I show the 45 minute countdown on a projector?

Yes. Open it on the presenting screen and press F for edge-to-edge digits at high contrast.

Does it keep time if I switch tabs?

Yes. It reads the system clock rather than counting frames, so a background tab or a locked screen will not make it drift.

Is the 45 minute countdown free to use?

Yes, for personal and commercial use, with no sign-up and no limit. Use it in classrooms, gyms and streams without asking.