NH34 vs NH35 vs NH36: Which One Should You Actually Choose?
Seiko may have created the NH movements to supply the growing microbrands industry back then (as opposed to just selling their in-house movement without rebranding), but it also supported the growth of Seiko mods, or personally built watches.
The 3 most widely used ones are the NH34, NH35, and NH36, which have very similar specifications and very different use cases. Picking the right movement matters more than most beginners realize because it affects what features your watch can actually use. The good news is that this choice is not complicated once you understand what each movement is meant to do.
NH Movements and SII vs TMI
Seiko makes movements through different companies for different audiences. SII, or Seiko Instruments Inc., makes movements like the 4R, 6R and 8R series that are used mainly in Seiko’s own watches. These movements are not easy for outside brands or modders to buy, although they also manufacture NH movements in some locations.
TMI, or Time Module Inc., is another Seiko-owned company that mainly makes movements for third parties. The NH series is basically the aftermarket version of Seiko’s in-house movements. For example, the NH35 is the same as the Seiko 4R35, and the NH36 matches the 4R36, and so on. The main difference is who they are sold to, not how they work.
This setup lets modders and microbrands use proven Seiko designs while Seiko keeps its branded watches separate. That is why NH movements have become the standard choice for affordable automatic watches.
Similarities and Differences of NH Movements
All NH movements share the same core features. They are automatic and can also be hand-wound. The seconds hand stops when you pull the crown, which makes setting the time easier. Power reserve is around 41 hours, and they beat at a smooth 21,600 vibrations per hour. Accuracy is also nothing to scoff at, rated at minus 20 to plus 40 seconds per day out of the box, which is normal for this price range.
They are based on the older 7S26 design but improved with hacking and hand-winding. Most models use 24 jewels and weigh about the same, so performance differences in real life are minimal.
The NH35 is the most common option. It has a date wheel for use with dials that have a window at 3 o’clock and fits most standard Seiko mod cases. Because of this, it is the default choice for most builds.
The NH36 is almost identical in size to the NH35 but adds a day display along with the date. The day wheel can come in different languages, with the most common ones being English, Japanese, and Arabic. This movement only makes sense if the dial has both day and date windows, like what you usually see on dive watches. Choose the NH36 only if the dial includes both day and date windows. Installing an NH36 in a date-only dial adds cost without visible functionality. Conversely, using an NH35 in a day-date dial creates a mismatch where one window sits empty. Match the movement to the dial configuration.
The NH34 adds a GMT function that tracks a second time zone using a 24-hour scale. It is similar in size to the other two, a commendable feat considering the GMT, though it does have a taller hand post than the NH35 and NH36, meaning it requires specialized modding parts. The main difference is that the crystal will need to be double domed, otherwise the hands would be touching its underside.
NH38 and NH39: No-Date Options
The NH38 and NH39 remove the date completely. This allows for clean, balanced dials without a date window. The NH38 works with open-heart dials that show part of the movement, while the NH39 is made for fully closed, symmetrical designs.
These movements are popular in dress watches, minimalist builds, and vintage-style designs. They also save you from resetting the date if you rotate between multiple watches.
Personalizing NH Movements
For most Seiko mods, NH movements are plug and play, with no additional hardware tweaks necessary. That said, modding the movement does allow for further customization, and it’s not so hard that you have to rely on a professional watchmaker’s help!
At the front, you can swap the day and date wheel to have a different color or design. Black wheels can complement stealthy mods, or you can change swap to a lumed wheel for lume-heavy set ups. We even have a roulette date wheel for the people who like to let it ride!
The backside can also be spruced up by swapping out the basic OEM rotor for something more intricately patterned. In our store you’ll have access to a few luxury-inspired designs like Cote de Geneve, Clous de Paris, Asanoha, and more, and all in different finishes to complement any mod. And if you feel up for the challenge, you can even customize the movement bridge, although that takes a higher degree of skill compared to the simpler rotor swap.
Wrap Up
The NH movement family is popular because it is reliable, affordable, and easy to work with. Other premium movements like Miyota are already available these days, but these beloved Seiko workhorses will always have a soft spot in our Seiko modder hearts.
If you’re ready to build your custom watch with one of these movements, head on over to our store and browse our ever-growing catalog of Seiko mod parts! We already have 600+ parts that work with these NH movements, and if you want something more premium or unique, we also have mod parts for Miyota movements and VK Mecaquartz too.
Happy modding!