If you are shopping for an affordable automatic, you will see two movement names again and again: the Seiko 4R36 and the NH35. They are close relatives. Here is what actually differs.
| Seiko 4R36 | Seiko NH35A | |
|---|---|---|
| Used in | Seiko’s own watches (Turtle, Samurai, Seiko 5 Sports) | Other brands (Invicta 8926OB and many microbrands) |
| Jewels | 24 | 24 |
| Beat rate | 21,600 vph | 21,600 vph |
| Power reserve | 41+ hours | 41 hours |
| Hacking / hand-winding | Yes / Yes | Yes / Yes |
| Display | Day and date | Date only (NH36A adds the day) |
| Rated accuracy | +45 / -35 s per day | -20 / +40 s per day (NH family) |
What this means when you buy
- Day or date? If you want the day wheel, look for a 4R36 or an NH36.
- Servicing. Both are common and cheap to service or replace.
- Brand. A 4R36 means a Seiko-branded watch; an NH35 usually means another brand, such as the Invicta 8926OB.
Want to see them next to the 6R35, Miyota 9015 or ETA 2824-2? Open the movement comparison. For the jargon, see the glossary.
Verdict
Treat them as equals for reliability. Choose on the watch, not the movement: the 4R36 if you want a Seiko with a day display, the NH35 if the watch you like happens to use it.
Frequently asked questions
Is the NH35 the same as the 4R36?
They are the same family. The 4R36 is Seiko’s own-brand version with day and date; the NH35A is the date-only version Seiko’s movement arm sells to other brands. The NH36A adds the day.
Which is more accurate?
Strapcode lists the 4R36 at +45 / -35 seconds a day. The maker figure for the NH family is quoted at -20 / +40. Real watches often do better once regulated.
Can I swap an NH35 into a Seiko?
Mechanically the family shares parts and dimensions, which is why modders use NH35s. Swapping one into a vintage Seiko makes it a franken, so it should be sold as modified.