NH36 Movement Explained: Day-Date, Specs & Mod Compatibility

The NH36 movement is what you reach for when a date window alone isn't enough. Built by Seiko Instruments Inc. (SII) — the same Seiko Group subsidiary behind the NH35 — it adds a day-of-week display to the familiar date, stacked in a dual window at 3 o'clock. That one complication is the whole story of this movement: it defines which dials you can use, which builds it belongs in, and why it exists alongside its more common sibling at all.

What the NH36 Actually Adds

The NH35 gives you an automatic with a single date display at 3 o'clock. The NH36 gives you date and day of the week in a dual display at the same position. The day wheel is bilingual — usually English/Kanji or English/Spanish, depending on the wheel installed.

If you want a build in the style of a Rolex Day-Date, or the classic Seiko 5 Sports look with day and date side by side at 3 o'clock, the NH36 is the movement that makes it possible. For every other dial layout, its sibling does the job — the full breakdown is in our NH35 vs. NH36 comparison.

NH36 Movement Specs at a Glance

Spec	Value
Manufacturer	Seiko Instruments Inc. (SII)
Beat rate	21,600 bph (6 ticks of the seconds hand per second)
Jewels	24
Power reserve	41 hours
Hand-winding	Yes
Hacking seconds	Yes
Date	Yes
Day of week	Yes (bilingual wheel)
Movement diameter	27.4 mm
Movement height	5.32 mm
Factory accuracy	-20 to +40 s/day
After regulation	±10 s/day realistic

Every number except the day display matches the NH35 exactly — same beat rate, same 41-hour reserve, same 27.4 mm × 5.32 mm footprint. Both movements hand-wind, both hack, and both accept a screw-down crown. Accuracy tolerance is identical too: the wide -20 to +40 s/day factory spec tightens to a realistic ±10 s/day once a watchmaker regulates the movement on a timing machine — €25-40 well spent on any mod build.

Setting Day and Date

The crown has three positions: winding, day/date setting, and time setting with hacking. Position 2 is where the NH36 differs from the NH35 in daily handling — you set the date by turning the crown one direction and the day by turning the other. One dial train, two calendar wheels, no extra pusher needed.

What the Day-Date Complication Means for Modding

Dial compatibility is strict. A dial cut for the NH35's single date window will not fit an NH36 — the day wheel physically blocks it, and the day window would either stay empty or land in the wrong spot. The reverse is just as true: an NH36 day-date dial won't work on an NH35. Choose the dial and the movement as a pair, never separately.

Hand sets carry over. Both movements share identical hand-shaft dimensions, so any hand set that fits the NH35 fits the NH36 too. Your hand choice never forces the movement decision.

The dial market is smaller. NH35-compatible dials outnumber NH36-compatible ones roughly 5-10x in the modding market. That's the honest trade-off: pick the NH36 because your build genuinely calls for a day-date layout, not for "more features" — in practice, hardly anyone checks the day display when a phone answers faster.

Cost is modest. The NH36 runs €70-110 for the bare movement versus €50-90 for the NH35. The upcharge is small; the dial constraint is the real price.

If you're sourcing from a donor watch instead of buying the bare movement: the current Seiko 5 Sports line, known as the SRPD or "5KX", is the classic NH36 donor, recognizable by its 4 o'clock crown.

Which MedoMods Watches Use the NH36

At MedoMods, the NH36 appears where a working day-date display is part of the design. The DAY MOD collection is its home — day-date builds inspired by the timeless Day-Date silhouette, running a genuine Seiko day-date movement behind sapphire crystal in a 316L stainless steel case, hand-assembled in Germany. The collection also carries date-only siblings on the NH35, so check the individual product page for the movement in a specific build.

Everything built on the date-only sibling lives in the NH35 Seiko mod overview — the larger half of the lineup, for every layout that doesn't need a day wheel.

FAQ

What is the difference between the NH36 and the NH35?

One complication: the NH36 shows both the day of the week and the date in a dual display at 3 o'clock, while the NH35 shows the date only. Beat rate, power reserve, jewel count, dimensions, and accuracy tolerance are identical.

Can I fit an NH35 dial on an NH36 movement?

No. A dial cut for the NH35's single date window doesn't work mechanically on the NH36 — the day wheel physically blocks it, and the day window would either stay empty or sit in the wrong spot. Dials must match the movement, in both directions.

How accurate is the NH36?

The factory tolerance is -20 to +40 seconds per day, the same as the NH35. After regulation on a timing machine (typically €25-40), ±10 s/day is realistic for most examples.

What languages does the NH36 day wheel show?

The day display is bilingual — usually English/Kanji or English/Spanish, depending on the wheel installed.