Seiko NH35 vs NH36: Complete Movement Comparison Guide

What Is the Seiko NH35 Movement?

The Seiko NH35A represents Seiko's most widely used automatic movement in the affordable watch segment. Introduced as the successor to the 7S26 caliber, the NH35 powers countless watches from sub-$200 Seiko 5 models to premium custom builds exceeding $500. Its popularity stems from proven reliability, widespread parts availability, and the addition of features absent in older Seiko movements—most notably hacking seconds and hand-winding capability.

Core Technical Specifications

The NH35 operates at 21,600 vibrations per hour (3 Hz), providing smooth second-hand motion while balancing accuracy with power efficiency. The movement delivers a 41-hour power reserve when fully wound, sufficient for most single-watch wearers who rotate their timepiece daily. With 24 jewels reducing friction at critical pivot points, the NH35 achieves typical accuracy of -20 to +40 seconds per day out of the box, improving to ±10-15 seconds daily after break-in and regulation.

The Date Complication

The NH35's defining feature is its date display positioned at 3 o'clock. The date wheel cycles through 31 days and requires manual adjustment for months with fewer days (February, April, June, September, November). Date changes occur at midnight with approximately 2 hours of transition time. The date wheel is available in multiple colors—white, black, red, and occasionally custom colors for specialty builds—allowing modders to match dial aesthetics.

Hacking and Hand-Winding

Unlike the older 7S26 that lacked these features, the NH35 includes hacking seconds: pulling the crown to the time-setting position stops the second hand, enabling precise synchronization. The movement also supports hand-winding via the crown, useful when the watch has stopped or for topping up power reserve without wearing the watch.

Why NH35 Dominates the Market

The NH35's popularity in both factory watches and custom builds stems from several factors:

Widespread Availability: Movement suppliers worldwide stock NH35 calibers, making replacement and sourcing straightforward.

Standardized Parts: Dial feet positions, stem height, and case compatibility follow Seiko standards, simplifying the modding process.

Proven Reliability: Millions of NH35 movements have operated for years across diverse conditions, establishing a track record of dependable performance.

Versatile Date Function: Most watch wearers prefer date complications, making the NH35 suitable for daily-wear timepieces where practical functionality matters.

What Is the Seiko NH36 Movement?

The Seiko NH36A shares the NH35's core architecture but adds a day-of-week display above the date window. Both complications stack vertically at the 3 o'clock position, creating a day-date configuration reminiscent of vintage Seiko aesthetics from the 1970s. While less common than the NH35 in the modding community, the NH36 serves specific use cases where the additional complication provides value.

Core Technical Specifications

The NH36 operates with identical mechanical specifications to the NH35:

• Frequency: 21,600 vibrations per hour (3 Hz)
• Power Reserve: 41 hours
• Jewels: 24
• Accuracy: -20 to +40 seconds per day (typical)
• Hacking Seconds: Yes
• Hand-Winding: Yes

The only mechanical difference lies in the calendar complication module—the NH36 includes an additional day wheel mechanism.

The Day-Date Complication

The NH36 features both day and date displays at 3 o'clock. The day window appears above the date window, with both complications visible through rectangular windows on the dial. Day wheels are available in multiple language pairs to serve different markets:

• English/Spanish
• English/German
• English/French
• English/Arabic
• English/Japanese (Kanji)

The bilingual day wheel allows users to select between two languages, with the day abbreviation appearing in the chosen language (e.g., "MON" or "LUN" for Monday/Lunes in English/Spanish wheels).

Crown Operation

The NH36 requires an additional crown position compared to the NH35:

• Position 1: Hand-winding (crown pushed in, rotated clockwise)
• Position 2: Quick-set day and date (first pull)
• Position 3: Time setting with hacking engaged (full pull)

In Position 2, rotating the crown clockwise advances the date, while counterclockwise rotation advances the day. Important: Quick-setting the day or date between 9 PM and 3 AM can damage the calendar mechanism, as the automatic change is already in progress during this window. Always advance time past 6 AM before quick-setting complications.

Why NH36 Is Less Common

Despite adding functionality, the NH36 sees less adoption in custom builds compared to the NH35 for several reasons:

Dial Design Constraints: The stacked day-date windows require more dial space, limiting design flexibility. Many modders prefer the cleaner appearance of date-only or no-date layouts.

Target Audience Preferences: Watch enthusiasts building custom pieces typically prefer either date-only (NH35) for versatility or no-date (NH38) for minimalist aesthetics. The day-date complication often feels redundant to this demographic.

Factory Watch Dominance: The NH36 appears primarily in budget factory Seiko watches ($120-$300 range), where the added complication provides perceived value for entry-level buyers.

Establishing Comparison Framework: Movement Selection Criteria

Quick Comparison: NH35 vs NH36 at a Glance

5 Key Differences: NH35 vs NH36

1. Complication Utility and Daily Functionality

NH35 Date-Only Display: The NH35 provides a date window at 3 o'clock—a complication most watch wearers use regularly. Tracking the date proves useful for scheduling, planning, and general awareness. However, the NH35 omits the day-of-week display, which some users prefer for quick visual reference without checking their phone or calendar.

NH36 Day-Date Display: The NH36 adds day-of-week tracking above the date. For users who frequently need to know what day it is—retirees, shift workers, or those with irregular schedules—this additional complication provides tangible utility. The bilingual day wheel allows users in multilingual regions to switch between languages based on context.

Practical Reality: Most modern watch wearers carry smartphones displaying both date and day prominently on the home screen. This makes the NH36's additional complication less critical than it was in previous decades. The date-only display of the NH35 strikes a balance between functionality and simplicity for contemporary users.

Winner: NH35 for most users; NH36 for specific use cases (vintage homages, users who prefer analog day tracking).

2. Dial Design and Aesthetic Flexibility

NH35 Design Freedom: The single date window at 3 o'clock offers significant dial layout flexibility. Watchmakers can place hour markers, Arabic numerals, or indices at most positions, with only the 3 o'clock position requiring accommodation for the date window. The date wheel color can be matched to dial aesthetics (white on white dial, black on black dial, contrasting colors for visual interest).

NH36 Design Constraints: The stacked day-date windows require approximately twice the vertical space compared to the NH35's date-only window. This larger opening limits dial design options—the 3 o'clock area must remain clear of any markers or text. For certain dial styles (particularly those with Arabic numerals at 3), the day-date complication creates visual imbalance or forces design compromises.

Modding Perspective: Watch modders building custom pieces overwhelmingly prefer the NH35's design flexibility. The single date window integrates more easily into Submariner-style, GMT-style, or dress watch dials. The NH36's day-date window works best in vintage-inspired builds specifically designed around this complication, such as Seiko 5 SNK homages.

Winner: NH35 for design versatility; NH36 for specific vintage aesthetics.

3. Operational Complexity and Daily Use

NH35 Operation: The NH35's two crown positions keep operation straightforward:

• Position 1 (pushed in): Hand-wind by rotating clockwise
• Position 2 (pulled out): Set time (hacking engages)

Quick-setting the date requires rotating the hands forward past midnight to advance the date one day at a time. This method, while slower than a dedicated quick-set position, avoids the risk of damaging the calendar mechanism.

NH36 Operation: The NH36's three crown positions add complexity:

• Position 1 (pushed in): Hand-wind by rotating clockwise
• Position 2 (first pull): Quick-set day (counterclockwise) and date (clockwise)
• Position 3 (full pull): Set time (hacking engages)

The additional crown position simplifies date and day adjustments but introduces the risk of damage if quick-setting occurs during the 9 PM to 3 AM window when automatic calendar change mechanisms are engaged.

Maintenance Consideration: The NH36's additional calendar complication module includes more components that can wear over time. While both movements share similar long-term reliability, the NH36's day-wheel mechanism represents an additional failure point—albeit a rare one under normal use.

Winner: NH35 for operational simplicity; NH36 for faster calendar adjustments (with proper precautions).

4. Movement Availability and Sourcing

NH35 Availability: The NH35 is the most readily available Seiko movement worldwide. Major suppliers stock NH35 calibers consistently, and lead times for orders rarely exceed a few days. This widespread availability extends to replacement parts—dial feet, stems, rotors, and internal components are standardized and easy to source.

NH36 Availability: While still available from most movement suppliers, NH36 stock is less predictable than NH35. Some suppliers maintain limited NH36 inventory due to lower demand from modders. For custom builds, this can mean longer wait times or substituting NH35 instead. Factory watches using NH36 remain readily available, as Seiko continues producing NH36-powered watches for the budget segment.

Pricing Comparison: NH35 movements typically cost $35-$50 from aftermarket suppliers, while NH36 movements range $38-$52. The price difference reflects lower production volumes and demand for NH36 rather than increased manufacturing complexity.

Winner: NH35 for sourcing ease and inventory availability.

5. Use Case Alignment and Target Audience

NH35 Versatility: The NH35 serves the broadest range of use cases:

• Daily Wear Watches: Date function provides practical utility without unnecessary complications
• Custom Mod Builds: Submariner homages, GMT-style builds, dress watches, dive watches
• Tool Watches: Field watches, pilot watches, sports watches where date matters but day does not
• First Automatic Watch: New automatic watch owners appreciate the date complication without day-date complexity

Brands like SKYRIM, Orient, and budget Seiko lines use NH35 movements in watches targeting enthusiasts who value mechanical movements with practical date functionality.

NH36 Niche Appeal: The NH36 serves more specific use cases:

• Vintage Seiko Homages: 1970s Seiko 5 builds where day-date windows are authentic to the era
• Budget Factory Watches: Entry-level Seiko 5 models ($120-$250) where day-date adds perceived value
• Retirement Watches: Users with flexible schedules who benefit from day-of-week tracking
• Bilingual Markets: Regions where bilingual day wheels provide practical language flexibility

The NH36 appeals less to watch modders and enthusiasts, appearing primarily in factory watches targeting budget-conscious buyers or vintage aesthetic preferences.

Winner: NH35 for broad versatility; NH36 for specific vintage and budget applications.

Which Movement Should You Choose?

Choose NH35 If:

• Building Custom Mods: You're assembling a Submariner, GMT, or dress watch build requiring design flexibility
• Daily Wear Versatility: You want a date complication without day-date complexity
• Sourcing Simplicity: You prefer readily available movements with consistent inventory
• Modern Aesthetics: Your watch design prioritizes clean dial layouts with minimal complications
• First Automatic Watch: You're new to mechanical movements and want practical date functionality
• Broad Compatibility: You need a movement compatible with the widest range of dial designs and case styles

Choose NH36 If:

• Vintage Seiko Aesthetic: You're building a 1970s Seiko 5 homage requiring authentic day-date windows
• Day-Week Tracking: You genuinely use day-of-week displays for schedule management
• Bilingual Preference: You operate in multilingual environments and want language flexibility
• Budget Factory Watch: You're purchasing an entry-level Seiko and appreciate the added complication
• Retirement/Flexible Schedule: You have irregular daily routines where day tracking proves useful
• Specific Design Vision: Your dial design specifically incorporates day-date windows as a feature

Featured NH35 Watches from SKYRIM WRIST

SKYRIM Mod Royal Oak Blue

The Mod Royal Oak Blue from SKYRIM demonstrates how the NH35 movement enables accessible automatic watches for young professionals entering mechanical horology. This 41mm timepiece features SKYRIM's implementation of the NH35 caliber, balancing reliable timekeeping with the iconic Royal Oak-inspired octagonal bezel and integrated bracelet design. The blue dial with date window at 3 o'clock reflects SKYRIM's design philosophy: leveraging proven Best Seiko movements to deliver timeless aesthetics without luxury premiums. This model is particularly popular among SKYRIM's core demographic of 25-35-year-old professionals for its versatility across casual and business casual settings.

Product URL: https://www.skyrimwrist.com/products/mod-royaloak-8