Automatic or quartz Seiko mod: which one should you choose?

When choosing a Seiko mod, one question always comes up: automatic or quartz? Both have their advantages, and the right choice mostly depends on how you wear a watch. In this guide, we simply compare the three Seiko movements we use in our watches: the NH35A, the NH34 and the VK63.

The difference in one sentence

An automatic Seiko mod runs without a battery: it winds itself with the motion of your wrist. A quartz Seiko mod runs on a battery: it's ultra accurate and needs no winding.

The automatic Seiko mod: mechanical charm

In an automatic watch, a small rotor spins with every movement of your arm and winds the mainspring that drives the hands. That's what gives the seconds hand its smooth, sweeping motion that enthusiasts love.

The Seiko NH35A movement

It's the most widely used automatic movement in the Seiko mod world, and for good reason:

• About 41 hours of power reserve: left on a table, your watch keeps running for almost two days.
• Manual winding through the crown, if you haven't worn it for a while.
• Hacking seconds: the seconds hand stops when you pull the crown, so you can set the time to the second.
• Robust and easy to service, with parts available everywhere.

You'll find it in our Subeiko dive Seiko mod and in our classic Justeiko, Dayteiko and Yachteiko models.

The Seiko NH34 movement: the automatic GMT

The NH34 takes the NH35A base and adds a fourth GMT hand that makes one turn every 24 hours. With the graduated bezel, it lets you read two time zones at once. It's the heart of our Seiko mod GMT, the GMTeiko collection, perfect if you travel or have loved ones on the other side of the world.

The quartz Seiko mod: accuracy and simplicity

A quartz watch is powered by a battery and a tiny quartz crystal that vibrates at a very stable frequency. The result: a watch that always keeps time, even if it sits in a drawer for weeks.

The Seiko VK63 movement: the quartz chronograph

The VK63 is a quartz chronograph that's very popular for sporty Seiko mods:

• Very accurate: far more than an automatic movement in daily use.
• No winding: put it on and it's on time.
• A real chronograph: the chrono hand starts, stops and snaps back to zero, with a feel close to a mechanical chrono.
• A battery that lasts several years, easy to replace at any watchmaker.

It's the movement in our chronographs, like the Seitona Seiko mod chronograph, the most popular watch in the store.

Automatic vs quartz: the comparison

So, which Seiko mod should you choose?

Choose an automatic Seiko mod if:

• you wear your watch almost every day;
• you love the idea of a "living", mechanical watch with no battery;
• you're looking for a diver, classic or GMT watch.

Choose a quartz chronograph Seiko mod if:

• you want a watch that always keeps time without thinking about it;
• you rotate between several watches;
• you love the sporty three-sub-dial look.

Many of our customers end up owning both: an automatic for every day and a chronograph to switch up their style.

FAQ

Does an automatic watch need to be worn every day?
No. If it stops, just give the crown a few turns to wind it and reset the time.

Is quartz less "high-end"?
Not at all. Quartz is more accurate, and a quartz chronograph offers functions you often only find on much more expensive mechanical watches.

Are both water resistant?
Yes. Every Eternal Mods Seiko mod is tested to 10 bar before shipping, whether automatic or quartz.

Find your Seiko mod

Automatic or quartz, every Eternal Mods watch is hand-assembled, tested to 10 bar, covered by a 2-year warranty and shipped for free. Discover all our Seiko mods, or read our complete Seiko mod guide to learn everything before you choose.