Seiko NH36 Movement: Complete Technical Guide 2026

The Seiko NH36 is an automatic movement manufactured by Seiko Instruments Inc., featuring a day-date complication that displays both the day of the week and date through windows on the dial. Operating at 21,600 vibrations per hour (vph) with 41-hour power reserve, the NH36 includes hacking seconds and hand-winding capability—making it the day-date variant of the popular NH35 caliber.

This movement powers countless affordable automatic watches from microbrands, Seiko's own lineup (branded as 4R36), and custom watch builds. The day-date complication adds practical functionality for daily wearers who want to check both day and date at a glance. This guide covers complete specifications, NH36 vs NH35 comparison, accuracy expectations, and guidance on whether the NH36 suits your needs.

Seiko NH36 Technical Specifications

Understanding the NH36's specifications reveals its position in Seiko's movement hierarchy and its suitability for different watch applications:

What the Specs Mean in Practice

The NH36 shares its core architecture with the NH35—identical diameter, thickness, frequency, power reserve, and jewel count. The critical difference is the day-date complication: where the NH35 shows only the date, the NH36 adds a day-of-week display through an additional wheel mechanism.

The 21,600 vph frequency produces a 6-beat-per-second sweep that's slightly less smooth than higher-beat movements (28,800 vph) but offers excellent balance between accuracy and durability. The 41-hour power reserve means removing your watch Friday evening still finds it running Sunday morning—practical for weekend rotation.

Hacking seconds (stopping the seconds hand when pulling the crown) enables precise time-setting to atomic clocks or phone displays. Hand-winding capability lets you manually wind the mainspring when the watch has stopped—a convenience the NH36 shares with its NH35 sibling but which older Seiko movements like the 7S26 lack.

NH36 vs NH35: Understanding the Difference

The NH36 and NH35 are the most commonly compared Seiko movements. Understanding their relationship helps buyers choose the right caliber for their needs.

The Only Difference: Day Complication

The NH36 and NH35 are mechanically identical except for the day-date versus date-only complication. They share the same base caliber, accuracy specifications, and reliability record. The NH36 simply adds the day wheel mechanism that displays the day of the week alongside the date.

This means identical dimensions—watches designed for NH35 movements can accept NH36 with appropriate dial modifications for the day window. The wholesale price difference ($5-10 more for NH36) reflects the additional day wheel components.

Which Should You Choose?

Choose NH36 when: You want both day and date information at a glance. The day-date complication is particularly useful for office workers, travelers, and anyone who loses track of days. Classic designs like Rolex Day-Date homages require the NH36's day wheel.

Choose NH35 when: You prefer cleaner dial designs without the day window, or you're building/buying a watch where the day complication isn't part of the aesthetic (dive watches, field watches, minimalist designs). The NH35's date-only window offers more dial design flexibility.

Many watch brands make this choice for you based on their design goals. Brands like SKYRIM, for example, use NH35 for their Submariner and Explorer builds (date-only designs) while choosing Miyota 8285 rather than NH36 for their Day-Date collection—demonstrating that movement selection depends on specific design and performance requirements.

NH36 vs 4R36: Same Movement, Different Names

A common question: what's the difference between NH36 and 4R36? The answer is simple—they're the same movement with different branding.

The Naming Convention

4R36: The designation Seiko uses for movements in their own branded watches (Seiko 5, Presage, etc.). When you buy a Seiko watch with a 4R36 movement, you're getting the movement with Seiko's internal branding and quality control standards.

NH36: The designation Seiko Instruments Inc. uses when selling the same movement to third-party watch manufacturers. Microbrands, custom builders, and non-Seiko companies buy NH36 movements for their watches.

Mechanically, these movements are identical—same specifications, same factory, same production line. The only differences are the branding on the rotor (if visible) and the distribution channel. Some argue that 4R36 movements receive slightly more rigorous quality control for Seiko-branded products, but this distinction is largely theoretical—both variants deliver the same real-world performance.

Seiko-Branded Equivalents

For reference, here's how Seiko's internal naming maps to NH-series movements:

• 4R35 = NH35: Date-only automatic
• 4R36 = NH36: Day-date automatic
• 4R34 = NH34: GMT automatic
• 4R38 = NH38: No-date automatic
• 4R39 = NH39: Open heart automatic

NH36 vs Miyota 8285: Day-Date Alternatives

For buyers specifically seeking day-date functionality, the Miyota 8285 offers an alternative to the NH36. Both power popular affordable automatic watches with day-date complications.

Key Differences

Hacking and Hand-Winding: The NH36's biggest advantages are hacking seconds and hand-winding capability—features the Miyota 8285 lacks. If precise time-setting matters to you, or if you want to manually wind a stopped watch rather than shaking it, the NH36 is the better choice.

Parts Ecosystem: The NH36 benefits from Seiko's extensive aftermarket parts availability. Dials, hands, and modification components are widely available for NH35/NH36 movements. Miyota movements have more limited aftermarket support.

Brand Preference: Some brands prefer Miyota movements for cost or supply chain reasons. SKYRIM's Day-Date collection uses Miyota 8285 ($285) rather than NH36, demonstrating that both movements deliver reliable day-date functionality at similar price points. The choice often reflects brand-specific engineering decisions rather than clear superiority of either movement.

How the NH36 Works

The NH36 operates like all automatic movements: a weighted rotor spins with wrist motion, winding the mainspring through a gear train. The day-date complication adds mechanical complexity that's worth understanding.

The Automatic Winding System

The NH36's bidirectional rotor winds the mainspring whether it spins clockwise or counterclockwise. This maximizes winding efficiency from natural wrist motion—walking, gesturing, and general activity all contribute to power reserve. Eight hours of typical wear fully charges the 41-hour reserve.

The hand-winding capability lets you bypass the rotor system entirely, winding the mainspring directly through the crown. Rotate the crown clockwise 20-30 times when the watch has stopped to start it before wearing.

The Day-Date Mechanism

The NH36's day-date mechanism uses two independently operating wheels:

Date Wheel: Advances once daily at midnight (or near-midnight, depending on regulation). The date window typically appears at 3 o'clock, showing numbers 1-31.

Day Wheel: Also advances at midnight, displaying the day of the week through a separate window. Most NH36 configurations show the day above the date at 3 o'clock, though dial design varies.

Both wheels can be quick-set by pulling the crown to the second position and rotating—clockwise for date, counterclockwise for day (or vice versa depending on dial configuration). Never adjust day or date between approximately 9 PM and 3 AM when the mechanism is engaged—doing so risks damaging the day-date wheels.

Hacking Seconds

When you pull the crown to the time-setting position, a small lever contacts the balance wheel and stops it. This "hacking" feature lets you synchronize the seconds hand to a reference time source. Pull the crown, wait for the reference to reach the desired second, then push the crown in to release the balance wheel and start the watch in sync.

NH36 Accuracy and Regulation

Factory specifications rate the NH36 at -20 to +40 seconds per day—a fairly wide tolerance that most units beat significantly in practice.

Real-World Accuracy

Most NH36 movements out of the box run between +10 to +25 seconds per day. Units can be regulated to achieve ±10 seconds daily or better by a competent watchmaker. The movement's relatively simple construction makes regulation straightforward compared to more complex calibers.

Factors affecting accuracy include:

• Position: Accuracy varies in different positions (dial up, crown up, etc.)
• Temperature: Metal components expand/contract with temperature changes
• Magnetism: Magnetic fields from phones/speakers can affect the balance spring
• Power reserve level: Some movements run faster when fully wound, slower when depleted
• Activity level: Sedentary days may result in lower power reserve affecting accuracy

Improving Accuracy

If your NH36 watch consistently runs fast or slow beyond acceptable limits (±30 seconds daily), professional regulation can correct this. A watchmaker adjusts the regulator—a small lever that changes the effective length of the balance spring—to speed up or slow down the movement. This service typically costs $30-50 and takes minutes in skilled hands.

Advantages of the NH36 Movement

The NH36 offers several practical benefits that explain its popularity:

Day-Date Convenience: Seeing both day and date at a glance helps daily orientation, especially for office workers and travelers who lose track of days. The complication adds genuine utility without significant complexity.

Hacking and Hand-Winding: These features, absent in the competing Miyota 8285, provide practical advantages. Hacking enables precise time-setting; hand-winding eliminates the need to shake a stopped watch to start it.

Proven Reliability: Millions of NH36/4R36 movements power watches worldwide. The caliber's track record spans decades with minimal reported issues. Seiko's manufacturing consistency ensures predictable performance.

Affordable Service: When service is eventually needed (every 5-7 years typically), NH36 parts are widely available and inexpensive. Any competent watchmaker can service this movement—you're not locked into brand-specific service networks.

Extensive Parts Ecosystem: The NH35/NH36 family shares dial and hand dimensions, creating a massive aftermarket parts selection. Watch builders can source hundreds of dial designs, hand styles, and modification components.

Limitations of the NH36 Movement

Understanding the NH36's limitations helps set appropriate expectations:

Lower Beat Rate: The 21,600 vph frequency produces visible "stepping" in the seconds hand sweep compared to 28,800 vph movements. Enthusiasts who prioritize smooth sweep may prefer higher-beat alternatives like the Miyota 9015.

Day-Date Window Constraints: The day-date complication requires specific dial cutouts and limits design flexibility. Not all dial styles accommodate the dual window aesthetically. Date-only (NH35) or no-date (NH38) movements offer more design freedom.

Factory Accuracy Tolerance: The -20 to +40 seconds/day specification is wider than some competitors. While most units perform better than spec, buyers seeking chronometer-grade accuracy should look elsewhere or budget for professional regulation.

No Quick-Set Day: Unlike some movements that allow independent day adjustment, the NH36's day wheel advances with the date or through the crown—there's no separate quick-set for day alone on most implementations.

NH36 vs Other Day-Date Movements: Complete Comparison

For buyers evaluating day-date movement options, this comprehensive comparison helps understand how the NH36 stacks up against alternatives across different price points and feature sets:

NH36 vs ETA 2836-2: The Swiss ETA offers higher beat rate (smoother sweep) and tighter factory tolerances, but costs 3-4x more wholesale. For budget-conscious buyers, the NH36 delivers 90% of the functionality at 25% of the cost. The ETA justifies its premium in luxury watches where Swiss heritage matters.

NH36 vs Miyota 8285: Both Japanese movements deliver reliable day-date functionality, but the NH36's hacking and hand-winding features provide practical advantages. Brands like SKYRIM's Day-Date collection use the Miyota 8285 ($285), demonstrating that both movements power quality affordable timepieces. The choice often reflects brand engineering preferences rather than movement superiority.

Watches Using the NH36 Movement

The NH36/4R36 powers watches across many price points and styles. Understanding where this movement appears helps buyers identify quality day-date options:

Seiko-Branded Watches (as 4R36)

Microbrand Day-Date Watches

Numerous microbrands use the NH36 for day-date automatic watches. When evaluating these options, prioritize:

• Crystal: Sapphire crystal resists scratches far better than mineral glass
• Case Quality: 316L or 904L stainless steel indicates premium construction
• Finishing: Hand-brushed and polished surfaces indicate attention to detail
• Water Resistance: 50m minimum for daily wear confidence

Day-Date Alternatives: SKYRIM Mod Collection

For buyers seeking classic Day-Date aesthetics, SKYRIM offers an alternative approach using the Miyota 8285 movement. While not NH36-powered, the SKYRIM Mod Day-Date collection ($285) delivers day-date functionality with sapphire crystal, exhibition caseback, and premium finishing—demonstrating how different movement choices serve similar design goals.

SKYRIM's broader collection uses NH35 movements for their Submariner-style divers and NH34 for GMT complications—showcasing how the NH-series family powers different watch types based on complication requirements.

Custom Builds

Watch modders and custom builders frequently use NH36 movements for Day-Date style builds. The movement's compatibility with aftermarket parts enables personalized day-date watches at accessible price points. Popular modifications include:

• Dial swaps with aftermarket day-date dials ($30-80)
• Hand upgrades to polished or lumed styles ($15-40)
• Case upgrades to 316L/904L steel ($80-150)
• Sapphire crystal installation ($25-50)

Maintenance and Service

The NH36's straightforward mechanical design makes it one of the most serviceable automatic movements available. Understanding maintenance requirements helps owners maximize movement longevity.

Service Intervals

Seiko recommends servicing the NH36 every 3-5 years for optimal performance. Daily wearers should service closer to the 3-year mark; occasional wearers can extend to 5 years. Signs indicating service is needed include:

• Accuracy degradation beyond ±40 seconds/day
• Power reserve dropping below 30 hours when fully wound
• Rough or gritty crown operation
• Day or date not changing cleanly at midnight

Service Costs

The NH36's affordable replacement cost ($35-50 wholesale) means full movement replacement often makes more economic sense than extensive repairs. A competent watchmaker can swap movements in 30-60 minutes, keeping total service costs under $100 in most cases.

DIY Maintenance Tips

Between professional services, owners can extend movement life through simple practices:

• Avoid the danger zone: Never adjust day or date between 9 PM and 3 AM when the mechanism is engaged
• Keep it wound: Watches sitting unworn for months should be manually wound and run periodically
• Avoid magnetism: Keep watches away from speakers, phones, and magnetic clasps—magnetism affects accuracy
• Crown care: Always push the crown fully in after setting; exposed crowns allow dust and moisture ingress

Frequently Asked Questions

What is the difference between NH35 and NH36?

The only difference is the day complication. The NH36 displays both day and date; the NH35 shows date only. All other specifications—frequency, power reserve, accuracy, dimensions, hacking, and hand-winding—are identical. Choose NH36 for day-date functionality; choose NH35 for date-only or cleaner dial designs.

Is the NH36 the same as 4R36?

Yes. NH36 and 4R36 are identical movements with different names. Seiko uses "4R36" for movements in their branded watches; "NH36" designates the same movement sold to third-party manufacturers. Mechanically, they're interchangeable.

How accurate is the Seiko NH36?

Factory specification is -20 to +40 seconds per day. Real-world performance typically runs +10 to +25 seconds daily. With professional regulation, ±10 seconds per day is achievable. Accuracy varies by position, temperature, and power reserve level.

How long does the NH36 power reserve last?

41 hours when fully wound. This means removing your watch Friday evening still finds it running Sunday morning. Daily wear maintains full reserve through normal wrist motion. The hand-winding feature lets you manually top up the reserve when needed.

Does the NH36 hack and hand-wind?

Yes to both. Pulling the crown to the time-setting position stops the seconds hand (hacking), enabling precise synchronization. Rotating the crown clockwise winds the mainspring manually (hand-winding), useful for starting a stopped watch without wearing or shaking it.

Is the NH36 better than Miyota 8285?

For day-date functionality, both deliver similar results. The NH36 offers hacking and hand-winding that the Miyota 8285 lacks—advantages for precise time-setting and convenience. The Miyota 8285 is equally reliable but trades these features for simpler operation. Neither is objectively "better"; the choice depends on whether hacking/hand-winding matter to you.

Conclusion

The Seiko NH36 delivers proven day-date functionality in an affordable, serviceable package. Its combination of day-date complication, hacking seconds, and hand-winding capability makes it the most feature-complete option in Seiko's NH-series lineup. The movement's reliability record, extensive parts availability, and accessible service costs explain its popularity among microbrands and watch builders.

Choose the NH36 when you want day-date functionality with the convenience of hacking and hand-winding. If the day complication doesn't appeal to you, the NH35 (date-only) or NH38 (no-date) offer the same reliability with cleaner dial options. For those seeking smoother seconds sweep, higher-beat alternatives like the Miyota 9015 trade some features for refined motion.

The NH36 isn't the most prestigious or accurate movement available—but it delivers genuine mechanical watchmaking at accessible prices, with the practical day-date complication that many wearers appreciate for daily use.