The Seiko NH movements get discussed as though they were rival calibres with different strengths. They are not. They are one movement with four different modules bolted to the top, and choosing between them is a question about what you want on the dial — not about quality, accuracy or durability.
That is the whole answer, and most comparison articles bury it. Here are the details anyway.
What they share
Every member of the family is built on the same base and carries identical core specifications:
- 24 jewels
- 21,600 vibrations per hour (3 Hz)
- Approximately 41 hours of power reserve
- Factory accuracy specified at −20 to +40 seconds per day
- Hand-winding
- Hacking seconds
- Made by Seiko Instruments for sale to third-party builders
So: no calibre in this family is more accurate than another, none has a longer reserve, and none is more reliable. Anyone telling you the NH36 is a "better movement" than the NH35 is describing a preference, not a specification.
NH35 — date only
A single date window, conventionally at three o'clock. This is the default, the volume seller, and for most people the right choice.
Choose it if you want the cleanest dial. One window interrupts the symmetry less than two, and on a dial with applied indices or a textured finish, less interruption is usually better. It is also the easiest to find parts for by a wide margin, which matters in five years when you want a different dial.
NH36 — day and date
Adds a day-of-week display, usually as a second window beside the date or as a wider combined aperture at twelve or three.
Choose it if you genuinely use the day display. Some people check it constantly; others have never once looked at it. Be honest about which you are, because the trade-off is real: two windows take more real estate out of the dial, and a day-date layout constrains which dials and hand sets will look balanced.
One practical note: the day wheel is usually available in more than one language pairing. Worth asking about before you order.
NH34 — GMT
Adds a fourth hand that tracks a second time zone against a 24-hour scale, read either on the dial or on a rotating bezel.
Choose it if you actually track two time zones — travel, family abroad, work across time zones. If you do, it is the most genuinely useful complication in the family and nothing else substitutes for it.
Two honest caveats. First, this is a "caller" GMT, not a "flyer": you adjust the second time zone rather than independently jumping the local hour hand, which is slightly less convenient when you land somewhere new. Second, the NH34 is newer and less abundant than the NH35, so parts and dial options are a smaller pool and prices run a little higher.
NH38 — no date
Drops the date entirely. Frequently paired with a dial aperture that exposes the balance wheel, which is why it is often called the open-heart option.
Choose it if you want a fully symmetrical dial, or you want to see the movement working. A no-date dial is a real aesthetic position, not a compromise — plenty of people find a date window the single most annoying thing about a watch.
A short way to decide
Ask one question: what do I want to read off this watch?
- Just the time, and a clean dial → NH38
- Time and the date → NH35
- Time, date and the day of the week → NH36
- Time, date and a second time zone → NH34
That is the entire decision. Do not let anyone sell you up through this list on the grounds that a higher number is a better movement. It is not a ladder — it is a menu.
The NH family is not the only option
Worth knowing, because plenty of builds use something else: Miyota calibres, made by Citizen's movement arm, cover the same ground and are just as repairable — our own Dayline Calendar day-date models use one. Meca-quartz movements such as the VK63 pair a quartz-regulated time display with a genuinely mechanical chronograph, which is how most affordable chronographs work, including our Speedline line. Neither is a downgrade; they are different tools. What matters is that the seller tells you which one is inside.
What actually differs between two mods
Since the NH movements are equivalent to each other, the real variables are everywhere else: case finishing, whether the crystal is sapphire, whether the bezel insert is ceramic or aluminium, whether the bracelet has solid end links, whether the dial is printed cleanly and sits dead centre, whether the hands are level, and whether the builder pressure-tested the case after assembling it.
Those are the things worth interrogating. The calibre is the part you can stop worrying about.
Our builds use the NH35 across the date models and the NH34 in the GMT models. If you want the longer explanation of the base calibre, that is in the NH35 guide.