Technique · Movements

NH35, NH34, NH38:
What's the difference?

Three Japanese automatic movements, three distinct characteristics. Everything you need to know to choose the right movement for your use and expectations.

7 min read

Modding Watches · Waimes

2025

The NH35, NH34, and NH38 are the three most used Seiko automatic movements in the modding world. Reliable, precise, affordable, but each has its specific features. Here's how to choose.

Why the choice of movement matters

In a Seiko mod, the movement is the heart of the watch. It determines the available functions (date, GMT, time-only), power reserve, and in some cases, the dial design since the date window's position must precisely match the intended opening.

Choosing the right movement from the start ensures a consistent, functional, and durable watch. Here are the details of the three references we use at Modding Watches.

NH35

The most versatile

24 jewels
41h power reserve
Date at 3 o'clock
Time-only + date
Compatible with all collections

NH34

⭑ The GMT

24 jewels
41h power reserve
Dual time zone
24h GMT hand
Ideal for travelers

NH38

The no-date

24 jewels
41h power reserve
No date
Cleaner dial
Minimalist design

The NH35: the universal reference

The NH35 is undoubtedly the most used movement in the Seiko modding world. Its popularity is explained by its versatility: it displays the time and date, adapts to a very wide variety of dials, and offers proven reliability for decades.

With 24 jewels and a 41-hour power reserve, it offers an accuracy of ±10 seconds per day. This is the movement we primarily use in our Nautilus Mod, Datejust Mod, Royal Oak Mod, and Santos Mod collections.

Key takeaway

The NH35 is the ideal choice if you want an elegant and versatile watch with a date. It's our most popular movement, used in 4 out of 5 collections at Modding Watches.

The NH34: the GMT for travelers

The NH34 is Seiko's GMT movement. It adds an essential function for travelers and enthusiasts: an additional hand that circles the dial in 24 hours, allowing two time zones to be read simultaneously.

This is the movement we exclusively use in our GMT Mod collection. Its two-tone bezel (red and blue, or red and black) allows for visual distinction between day and night in the second time zone.

“The GMT is much more than a technical function. It's an invitation to travel, worn on the wrist.”

— Modding Watches, Waimes

The NH38: the minimalist no-date

The NH38 is the no-date version of the NH35. Technically identical, it is distinguished by the absence of a date window, which allows for entirely clean dials, without visual interruption.

For minimal design enthusiasts, the NH38 offers additional creative freedom. The dial can be designed without positional constraints, opening up broader aesthetic possibilities.

Comparison table

Feature	NH35	NH34 GMT	NH38
Jewels	24	24	24
Power Reserve	41 hours	41 hours	41 hours
Date	Yes · 3h	Yes · 3h	No
GMT / 2nd Time Zone	No	Yes	No
Accuracy	±10 sec/day	±10 sec/day	±10 sec/day
Ideal for	Versatile	Travelers	Minimalist

Which one to choose?

The answer depends on your use and aesthetic desires:

You want an elegant and versatile watch → NH35. This is our recommendation for 80% of requests.
You travel often or are passionate about GMT → NH34. Dual time is a real everyday functionality.
You like a clean, no-date design → NH38. For those who want a perfectly clean dial.