Is my Seiko running right? Accuracy checker and fixes

An automatic watch is never perfect, and that is part of its charm. Here is how to measure your Seiko's accuracy in two minutes, what is normal, and what to do when it stops or runs badly.

How to measure it

1. Set the watch exactly to an atomic clock (search "time.is" on your phone) when the seconds hand passes 12.
2. Wear it as normal for 2–3 days.
3. Compare again, and enter how many seconds it is ahead or behind, and after how many hours.

Measuring over several days gives a far better answer than one night on the bedside table, because accuracy changes with position and how fully the watch is wound.

What is normal?

Seiko's official range for the 7S26 movement, when new, is −20 to +40 seconds a day. Vintage Seiko 5 movements were built to a similar standard. A 40-year-old watch that has not been serviced often runs a little further outside that, which is not a defect in itself. If it is far off, or getting worse, a service usually brings it back.

My Seiko stopped. What now?

• It has simply run down. These automatics can't be wound with the crown. Hold the watch and swing it gently from side to side for 30 seconds; it should start.
• It stops overnight. A full wind lasts around 40 hours, but a few hours on a quiet wrist may not wind it fully. Wear it for a full day, or give it a few extra swings in the morning.
• It stops even when worn, or the seconds hand stutters. The oils have probably dried out after decades. It's time for a service; don't keep forcing it.

Setting the date safely

Don't change the day or date between about 9 pm and 3 am on the watch's hands. In that window the date wheel is already moving, and forcing a quick-set can damage the mechanism. Move the hands to around 6 o'clock first, set the date, then set the time.

Not sure which movement you have? See Seiko 5 movements explained, or date your watch with our serial number decoder.