Seiko NH vs. Miyota Automatic Movements: What’s the Real Difference?

When you’re shopping for an affordable automatic watch or reviewing one for the fiftieth time, like some of us,, you’ll almost always see one of two movements inside: a Seiko NH series movement or a Miyota automatic movement. They’re the workhorses of the entry-level mechanical world, powering countless microbrands, homages, and even some big-name watches. But what actually separates them? Let’s break it down in a simple, watch-nerd-approved way.

Seiko NH Series (Most Common: NH35 / NH36)

The Seiko NH line is known for being rock-solid, reliable, and easy to service. These movements are based on the Seiko 4R family and are widely used because they’re inexpensive, durable, and nearly impossible to kill.

Key Specs:

• 21,600 bph (3 Hz)
• 24 jewels
• Hacking + hand-winding
• Power reserve: ~41 hours
• Known for durability and consistency
• Commonly seen in microbrand divers and field watches

Miyota 8000 & 9000 Series (Most Common: 8215 / 8315 / 9015)

Miyota—owned by Citizen—offers two tiers that often get compared to Seiko’s NH series. The 8000 series is their most affordable option, while the 9000 series is their step-up line known for being smoother and more refined.

Key Specs (8000 Series – Miyota 8215):

• 21,600 bph
• 21 jewels
• No hacking (most variants)
• Power reserve: ~42 hours
• Known for affordability but sometimes exhibits noticeable “stutter” in the seconds hand

Accuracy: Who Keeps Better Time?

Verdict: If accuracy is your priority and you’re comparing NH vs. Miyota 9000 series, Miyota wins. If you’re comparing NH vs. Miyota 8000 series, it’s essentially a tie.

Smoothness and Feel

Here’s where things get noticeable.

• Seiko NH: 21,600 bph gives you a standard “entry-level” sweep. Smooth, but not silky.
• Miyota 8215: Also 21,600 bph, but sometimes the seconds hand can stutter due to its indirect drive system.
• Miyota 9015: 28,800 bph means a smoother sweep closer to Swiss ETA/Sellita movements.

Verdict: Miyota 9015 feels more premium. NH and Miyota 8215 feel similar, but NH avoids the stutter issue.

Durability and Serviceability

This is where Seiko shines.

Seiko NH Series

• Widely available parts
• Easy to service
• Extremely tough
• Microbrands love them because they almost never come back for warranty repairs

Miyota Movements

• 8000 series: almost as durable as Seiko, but not quite as robust
• 9000 series: more refined but can be more sensitive
• Replacement parts are less common than complete movement swaps

Verdict: The NH series is the “Toyota Corolla” of watch movements. It's boring but ridiculously dependable.

Case Compatibility and Thickness

• Seiko NH movements are thicker, which means watches using them often end up chunkier.
• Miyota 9000 series is much thinner, allowing for sleeker designs and slimmer divers/dress pieces.
• Miyota 8215 is roughly similar in thickness to the NH but still slightly thinner.

Verdict: If you want a slim watch, Miyota (especially the 9000 series) is the better choice.

Which One Should You Choose?

Here’s the quick and simple rule:

Choose Seiko NH If You Want:

• Virtually bulletproof durability
• Low-cost servicing
• Stable performance
• No annoying seconds-hand stutter

Choose Miyota (8215) If You Want:

• Affordable, widely used microbrand movements
• Slightly thinner cases
• A strong alternative to Seiko when budget matters

Choose Miyota (9015) If You Want:

• Higher beat rate (28,800 bph)
• Slimmer, premium-feeling watches
• Better accuracy out of the box
• ETA/Sellita-like performance without the Swiss price tag

The NH series wins on ruggedness and ease of use, while Miyota offers more refinement and flexibility, specifically in the 9000 series. If you see either movement listed in a watch you’re considering, you can feel confident that you're getting a reliable, proven workhorse.

Check out some of the microbrands we offer that utilize these movements at our online store here: https://smallsecondswatchreviews.com/