NH35 vs Miyota 9015:
which should you want?

These two movements power most of the affordable mechanical watch market between them, and brands rarely explain why they chose one. The differences are real but narrower than the arguments about them suggest.

Last reviewed July 2026 · Independent guide · Not affiliated with NH35 and 9015

The difference you can see

The most obvious difference is beat rate. The 9015 runs at 28,800 vibrations per hour and the NH35 at 21,600, which translates to eight versus six increments of the seconds hand each second. Side by side the 9015 looks smoother; alone, most people would not notice unless they were told to look.

The second difference is thickness, and it has more practical consequence than beat rate. At roughly 3.9mm the 9015 is meaningfully slimmer, and because movement thickness largely determines case thickness, this is the difference you feel on the wrist rather than see on the dial.

A brand building a dress-proportioned automatic essentially has to use the 9015 or something like it, because the NH35 physically will not allow the case profile. Conversely a chunky dive watch has no need of the slimmer movement, which is one reason the NH35 dominates that category.

The differences you cannot see

Both movements carry 24 jewels, both hack, both hand-wind, and both offer power reserves in the low forties of hours. On paper, once you set aside beat rate and thickness, they are remarkably similar.

Reputation diverges more than specification. The NH35 has a strong record for tolerating shock, neglect and hard wear, which is part of why it is fitted to so many dive-style watches. The 9015, with its higher beat rate and finer tolerances, is generally regarded as slightly less forgiving, though not remotely fragile.

Accuracy potential favours the 9015 in theory, because a faster balance is less easily disturbed. In practice both arrive loosely regulated and both benefit substantially from a watchmaker’s attention, which usually matters more than which calibre you started with.

Cost, and what it means for the watch

The 9015 costs a brand more than the NH35, and that difference propagates. A brand choosing the 9015 has either accepted a lower margin or is positioning the watch slightly higher, and either way the choice tells you something about their priorities.

This makes the movement a reasonable proxy for a brand’s intent. A microbrand fitting a 9015 into a slim case is generally aiming at refinement. One fitting an NH35 into a robust case is generally aiming at durability and value. Neither is a compromise; they are different products.

Where it becomes a problem is when a listing says only “Japanese automatic”. That phrase spans both movements and a good deal else besides, and the ambiguity is almost always resolved in the cheaper direction. Ask which calibre, and treat a non-answer as an answer.

Which should you actually choose?

If you want the thinnest possible automatic, or you care about the smoothness of the seconds sweep, the 9015 is the answer and the premium is small in absolute terms.

If you want a watch to knock about, to wear in the sea, to not think about, or simply to spend as little as possible on while still owning something mechanical, the NH35 is at least as good a choice and arguably better. Its replaceability is a genuine feature: when a service costs more than the movement, being cheap to replace is worth something.

What should not drive the decision is a belief that one is meaningfully more reliable than the other. Both are mass-produced Japanese movements from major manufacturers with strong records. The failure modes people worry about are far less common than the internet suggests.

The most useful thing you can do is simply know which one you are buying, because that knowledge is what lets you judge whether the price is fair.