1-Minute Watch Lesson #010 – What Is Power Reserve ?

Power reserve tells you how long a watch will keep running when it’s not being worn.

In automatic and mechanical watches, energy is stored in a mainspring.
As it slowly unwinds, it powers the movement.

Most automatic watches offer around 38–42 hours of power reserve.
Some higher-end movements can go 3–5 days or more.

If you take off your watch and don’t wear it — the power reserve determines when it will stop.

That’s why some collectors use a watch winder…
while others simply reset the watch when needed.

The key takeaway?
Power reserve isn’t about accuracy — it’s about convenience and how often you’ll need to reset your watch.

A mechanical watch doesn’t just tell time — it stores it.