Seiko · Japan
Seiko NH35A
The NH35A was introduced around 2011 by TMI (Time Module Inc.), the industrial movement division of Seiko Instruments Inc. It is the OEM commercial designation for the same caliber that Seiko's consumer division markets as the 4R35 — both share the same movement architecture, differing primarily in commercial channel: 4R35 appears in retail Seiko-branded watches, NH35A is sold to third-party brands worldwide.
The movement traces its lineage to the legendary 7S26, Seiko's prolific automatic workhorse that lacked both hacking seconds and manual-winding capability. The 4R35/NH35A generation corrected both omissions — adding crown-stop hacking and hand-winding — while retaining the 7S26's 21,600 vph frequency, Magic Lever bi-directional winding system, and a compact form factor broadly compatible with cases designed for the older caliber.
The NH35A became the de-facto engine of the microbrand watch boom from roughly 2015 onward. TMI's low OEM pricing and reliable, easily serviced mechanics allowed hundreds of independent brands globally to offer genuine automatic movements at price points no Swiss caliber could match. It is one of the world's most popular third-party automatic movements.
Its closest competitors are Miyota's 8215 (same frequency, with hand-winding and stop-seconds in Miyota's current official specification) and 9015 (higher frequency, more refined finishing), and the ETA 2824-2/Sellita SW200-1 pairing at significantly higher cost. The NH35A's factory accuracy of −20 to +40 s/day is a conservative spec.
Hz
Jewels
Reserve
In catalog
Technical specification
| Manufacturer | Seiko |
| Origin | Japan |
| Type | Automatic |
| Beat rate | 21,600 bph · 3 Hz |
| Jewels | 24 |
| Power reserve | 41 h |
| Diameter | 27.4 mm |
| Height | 5.32 mm |
| Hacking seconds | Yes |
| Hand-winding | Yes |
| Date | Yes |
| GMT | No |
| Chronograph | No |
| Accuracy (stated) | -20/+40 s/day |
7 models
Watches with this caliber
FAQ
Is the Seiko NH35A automatic or manual?
The Seiko NH35A is an automatic (self-winding) movement: a rotor winds the mainspring from the motion of your wrist, so it needs no battery. It can also be wound by hand via the crown.
What is the power reserve of the Seiko NH35A?
About 41 hours on a full wind — into a second day, so it keeps running overnight off the wrist. Power reserve is how long the Seiko NH35A keeps running once you stop wearing or winding it.
Does the Seiko NH35A hack (stop the seconds when you set it)?
Yes. Pulling the crown stops the seconds hand, so the Seiko NH35A can be set precisely to a reference time before you push the crown back in. Hacking is what lets you sync several watches — or a watch and a phone — to the exact second.
Does the Seiko NH35A have a date function?
Yes — the Seiko NH35A can drive a date display, though whether a given watch actually shows the date depends on the dial the maker chose, so check the individual model rather than the movement.
How accurate is the Seiko NH35A?
The Seiko NH35A is rated at -20/+40 s/day. That is a normal working range for an uncertified mechanical movement; a COSC-certified chronometer is held to a tighter −4/+6 s/day, and a watchmaker can usually regulate one closer. Real-world accuracy still depends on how each watch is regulated, worn, and serviced.
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