Home / Guides / Seiko NH35 vs NH36

Seiko NH35 vs NH36

The Seiko NH35 and NH36 are the same movement in fit and function bar the calendar: the NH35 carries a date, the NH36 carries day and date.

One family, made by Seiko Instruments

The NH35 and NH36 come from Seiko Instruments, sometimes seen under the Time Module name, and are among the most common hacking automatics in enthusiast and microbrand watches. Both measure about 27.4mm across, both hack so the seconds hand stops for time-setting, and both hand-wind. They share the same footprint, which is a big part of why they are so widely used.

Because they are so close, choosing between them comes down almost entirely to the calendar you want.

Date versus day-date

The NH35 shows a date only. The NH36 adds a day disc, giving day and date together. That single difference decides which one your dial and case need, because the aperture cut in the dial has to match the calendar the movement drives. A date-only dial cannot show the NH36's day, and a day-date dial will have an empty or wrong window over an NH35.

So the calendar is the deciding factor, not the fit or the running, which are effectively the same.

Swapping within the family

Because they share a footprint, moving between the two is straightforward on the fit side, but you must match the dial to the calendar. Confirm the date-window or day-date position against your dial, and check hand-hole sizes as you would for any swap. Within the family the hands and general layout carry across, which keeps a like-for-like calendar swap simple.

Pick the NH35 for a clean date, the NH36 where you want day and date, and make sure the dial aperture matches whichever you choose.

Related

Sources: ETA/Sellita/Miyota/Seiko Instruments manufacturer technical sheets · Ranfft movement archive