Seiko NH vs 4R Movements: What's the Difference?

Quick Answer: Seiko NH and 4R movements are identical—same manufacturer (Seiko Instruments), same specifications, same reliability. The only difference is sales channel: NH series sold to third-party modders and microbrands, 4R series reserved exclusively for official Seiko-branded watches. NH35 = 4R35, NH36 = 4R36, NH38 = 4R38—functionally interchangeable.

This guide explains why Seiko uses dual designations, complete NH/4R equivalents, which offers better value, and whether NH movements qualify as "real Seiko" calibers.

The Core Difference: Sales Channel, Not Specifications

What Are NH Movements?

NH movements are automatic calibers manufactured by Seiko Instruments Inc. and sold to third-party watch builders—custom modders, microbrands, and independent watchmakers. The "NH" designation indicates third-party sales channel, enabling unrestricted use in non-Seiko watches.

Key characteristics:

• Third-party availability: Sold through movement suppliers to anyone building watches
• No Seiko branding restrictions: Can be used in any watch design without Seiko approval
• Identical specifications: Same components, tolerances, and quality control as 4R equivalents
• Lower movement cost: Modders pay $30-60 per NH35 movement versus retail watch pricing
• Custom mod ecosystem: Powers millions of Seiko-style custom watches globally

What Are 4R Movements?

4R movements are the same calibers manufactured by Seiko Instruments Inc., but reserved exclusively for official Seiko-branded retail watches. The "4R" designation indicates Seiko's internal caliber naming for movements installed in Seiko 5 Sports, Presage, and select Prospex models.

Key characteristics:

• Seiko-exclusive: Only found in official Seiko retail watches
• Official warranty coverage: Seiko manufacturer warranty (typically 3 years)
• Identical specifications: Same components, tolerances, and quality control as NH equivalents
• Higher retail pricing: Includes Seiko brand premium, case, dial, bracelet—complete watch package
• Authorized service network: Global Seiko service centers for warranty and repairs

Why Two Designations for Identical Movements?

Seiko Instruments Inc. (SII), Seiko's movement manufacturing subsidiary, operates as both supplier to Seiko Watch Corporation and independent movement manufacturer selling to third parties. This dual business model creates separate product lines:

4R series: Reserved for parent company (Seiko Watch Corporation) to maintain brand exclusivity. Seiko doesn't want "Seiko movement" appearing in competitor watches, so internal designation prevents brand dilution.

NH series: Marketed to external customers without Seiko branding. Third parties get reliable Japanese movements without Seiko trademark complications. SII profits from movement sales regardless of final watch brand.

This arrangement benefits everyone: Seiko maintains brand control, modders access proven movements affordably, and SII maximizes manufacturing volume across both channels.

Complete NH vs 4R Equivalents Table

Note: NH70 and NH72 skeleton variants exist only in NH designation—Seiko doesn't produce 4R skeleton movements for retail watches, leaving this niche to third-party modders.

Shared Specifications: Proof They're Identical

Core Specifications (All NH/4R Variants)

Every specification matches because they're the same movement. The designation difference exists purely for business reasons—sales channel separation, brand protection, and market segmentation—not quality or performance differentiation.

Manufacturing Process: Same Factory, Same Line

Both NH and 4R movements come from identical Seiko Instruments Inc. production facilities in Japan and overseas. Same automated assembly lines, same quality control procedures, same component suppliers, same testing protocols.

The only difference occurs at packaging: movements destined for Seiko Watch Corporation receive 4R designation and internal documentation, while movements for third-party sales receive NH designation and external distribution packaging.

A movement produced Monday morning might become 4R35 in a Seiko 5 Sports; one produced Monday afternoon might become NH35 shipped to a mod parts supplier. Manufacturing quality doesn't vary by designation.

Which Should You Choose?

Choose NH Movements (Custom Mods) If You:

• Want unique designs: NH movements enable custom dials, cases, hands, bezels impossible in Seiko's retail catalog
• Prioritize specific upgrades: Many NH mods include sapphire crystals and ceramic bezels at lower prices than equivalent Seiko models
• Accept build quality variance: Mod quality depends on builder reputation—research before purchasing
• Don't need official warranty: NH mods typically include builder warranty (1-2 years) rather than Seiko manufacturer coverage
• Appreciate mod culture: Value uniqueness and customization over brand recognition

Typical NH mod pricing: $200-500 for complete watches depending on materials and builder. Often includes sapphire crystal and ceramic bezel upgrades unavailable in similarly-priced Seiko retail models.

Choose 4R Movements (Official Seiko) If You:

• Want official Seiko branding: Dial says "Seiko," caseback says "Seiko"—brand recognition matters to you
• Need manufacturer warranty: Seiko's 3-year global warranty with authorized service network
• Prioritize consistent quality: Seiko's retail QC ensures consistent case finishing, bracelet fit, dial alignment
• Value resale recognition: "Seiko Presage" or "Seiko 5 Sports" resells easier than "Custom NH35 Mod"
• Prefer retail convenience: Buy from authorized dealers, no research required on builder reputation

Typical 4R Seiko pricing: $200-300 for Seiko 5 Sports (4R36), $450-550 for Presage (4R38 open-heart). Official warranty and authorized service included.

Price Comparison: Movement vs Complete Watch

Understanding pricing requires separating movement cost from complete watch cost:

Movement-only pricing (what modders pay):

• NH35/NH36: $30-50 per movement
• NH38/NH39: $40-60 per movement
• NH34 GMT: $50-70 per movement

Complete watch pricing:

• NH35 custom mod: $200-400 (movement + case + dial + hands + crystal + assembly)
• Seiko 5 Sports (4R36): $200-300 (official retail)
• NH38 open-heart mod: $250-450
• Presage Cocktail Time (4R38): $450-550

The movement costs roughly the same for both channels. Price differences reflect case quality, brand premium, warranty coverage, and material upgrades (sapphire vs Hardlex, ceramic vs aluminum).

Common Misconceptions Clarified

"NH Movements Are Lower Quality Than 4R"

False. NH and 4R movements are identical—same factory, same components, same quality control. The misconception stems from confusing movement quality with complete watch quality.

A poorly-assembled $150 NH mod might feel cheap because of case finishing or bracelet quality—not movement quality. The NH35 inside performs identically to a 4R35 in a $300 Seiko 5 Sports.

"NH Movements Aren't Real Seiko Movements"

False. NH movements are manufactured by Seiko Instruments Inc., a Seiko Group company. They're genuine Seiko-made calibers sold through different distribution channel. "Real Seiko" depends on your definition—made by Seiko? Yes. Branded as Seiko? No.

"4R Watches Are Always Better Value"

Not necessarily. A $350 NH mod with sapphire crystal and ceramic bezel may offer better materials than a $300 Seiko 5 Sports with Hardlex and aluminum bezel—despite identical movements. Value depends on what you prioritize: brand recognition vs material upgrades.

"NH Movements Can't Be Serviced"

False. Any watchmaker servicing 4R movements handles NH movements identically—same tools, same parts, same procedures. Parts availability matches exactly because they're interchangeable. Service costs run $150-250 regardless of designation.

Frequently Asked Questions

Is NH35 the same as 4R35?

Yes, identical. Same manufacturer (Seiko Instruments), same specs (24 jewels, 21,600 vph, 41-hour reserve), same components. Only difference: NH35 sold to third parties, 4R35 reserved for Seiko-branded watches. Performance, reliability, and service requirements match exactly.

Are NH movements made by Seiko?

Yes. NH movements are manufactured by Seiko Instruments Inc. (SII), a Seiko Group subsidiary. They're genuine Seiko-made calibers sold to third-party watch builders rather than reserved for Seiko-branded watches. Same factories, same quality control, same engineering.

Which is better: NH or 4R movement?

Neither—they're identical movements. The question is really "custom mod vs official Seiko watch." Choose NH mods for unique designs and potential material upgrades (sapphire, ceramic). Choose 4R Seiko watches for official branding, manufacturer warranty, and consistent retail quality.

Why are NH movements cheaper than 4R watches?

You're comparing movement cost to complete watch cost. NH35 movement costs $30-50; a complete NH35 mod costs $200-400. Seiko 5 Sports (4R36) costs $200-300 complete. Prices are comparable—the difference is brand premium, warranty coverage, and included materials, not movement cost.

Can Seiko service an NH movement watch?

Technically yes (same movement), but Seiko service centers typically only accept Seiko-branded watches. For NH movement service, use independent watchmakers—they service NH and 4R identically since parts interchange completely. Cost: $150-250 either way.

Conclusion

Seiko NH and 4R movements are identical calibers from the same manufacturer with different sales designations. NH35 = 4R35, NH36 = 4R36, NH38 = 4R38—same specs, same reliability, same 10-15 year service life. The distinction exists for business reasons (brand protection, market segmentation), not quality differentiation.

Choose based on what you're actually buying: NH movements power custom mods offering unique designs and material upgrades without Seiko branding. 4R movements come in official Seiko watches with manufacturer warranty and brand recognition.

Both deliver proven Seiko automatic reliability. The "better" choice depends on whether you value customization freedom or official brand backing—not movement quality, which is identical.