Guide
Watch Regulation Explained
Why your mechanical watch runs the way it does — and how to make it run better.
Quick answer: Regulating a watch means adjusting the balance so it runs closer to perfect time. A Seiko NH35 is specified at −20 to +40 seconds per day (Seiko's official spec); a watchmaker can often regulate it to within a few seconds a day. Accuracy also varies with position, temperature and wind level.
What regulation does
A small lever on the balance cock changes the effective length of the hairspring. Shorter makes the watch run faster; longer makes it slower.
What affects daily accuracy
- Position — dial up, crown down and so on all run slightly differently
- Wind level — a fully wound mainspring gives the most stable rate
- Temperature and magnetism
- Shocks and ageing oils
Tracking your watch's rate
Set it exactly to an online atomic clock, then check at the same time each day for a week. Divide the total drift by seven.
A simple trick
If your watch runs fast, rest it overnight dial-up or crown-down — one position usually runs slower and can cancel daytime gain.
Keep exploring
Frequently Asked Questions
Is +10 seconds a day normal?
Yes — well within the NH35's official spec of −20 to +40 seconds per day (Seiko's official spec).
Should I regulate my watch myself?
We recommend a watchmaker; opening the case affects water resistance.
Does magnetism affect accuracy?
Yes. A magnetised watch often gains minutes a day; a watchmaker can demagnetise it in seconds.