Seiko Instruments (SII, TMI) Caliber NH34

The Seiko Instruments (SII) caliber NH34A is an automatic movement based on the Seiko branded 4R34. As part of the NH family of movements, the notable feature in the NH34 is the GMT complication (24 hour hand). This movement was released in Summer 2022.

Caliber NH34 VS NH35:

The main difference between the NH34 discussed here and the NH35 is that the NH35 is a 3-hander with a date, while the NH34 adds the additional 24 hour hand.

Differences Between NH34, NH34A and NH34B?

NH34 is the base caliber number and the letter designates evolution or updates to the movement. In other words, the “A” in NH34A indicates that it is the first generation of this caliber. If they change something in the movement later, it will be called a NH34B. At the time of this post, only the NH34A exists.

NH34 Accuracy Rating:

Time Module claims that the accuracy of calibre NH34 is adjusted at the factory to keep the time between +40 / -20 seconds per day. This rating is based on normal daily wear on the wrist in temperatures between 2 ºC and 23 ºC. When testing your watch for timekeeping, make sure it is fully wound.

In Seiko’s own words:

“Due to the characteristics of mechanical watches, any actual daily rate may not fall within the range of time accuracy specified above dependent on the conditions of use, such as the length of time during which the watch is worn on the wrist, temperature, arm movement, and whether the mainspring is wound up fully or not, etc.” -Seiko User Manual

Power Reserve:

When your NH34 powered watch is fully wound, the power reserve is approximately 41 hours. When winding your watch, turn the crown clockwise slowly. You cannot overwind the movement.

NH34 Crown Position Functions:

0 (against the case): Clockwise = Manual Winding / Counterclockwise = Nothing
1 (pulled out one click): Clockwise = GMT hand / Counterclockwise = Date setting
2 (pulled out two clicks): Time setting clockwise and counterclockwise

Stem Removal:

To remove the stem, make sure the crown is in position 0 or normal position (not date or time setting position). There is a lever with a small indentation for your tool. Gently press down while pulling the stem out. See official instructions below for more guidance:

Replacement Cost:

Replacement prices for the caliber NH34A were found online in the range of $64.95 to $95 USD.

Recommended Service Intervals:

As per Seiko’s official recommended service intervals, they want 4R34 watches to be disassembled and cleaned by a Seiko service center once every 2 to 3 years “in order to maintain optimal performance of the watch for a long time”. Since the NH34A is based off of the 4R34, it is safe to assume the same recommendations apply. Ask the manufacturer of your watch for their recommendations.

In Seiko’s own words:

“The power transmission gear of the movement of this watch constantly receives force. To ensure that this mechanism works properly all the time, washing parts, changing oil, adjusting accuracy, checking functions and replacing consumable parts on a regular basis are important. The first overhaul after the purchase of your watch is particularly important for preserving long-time use of your watch. According to use conditions, the oil retaining condition of your watch mechanical parts may deteriorate, abrasion of the parts due to contamination of oil may advance or delay the time significantly, or the watch itself may stop.” -Seiko User Manual

Reference Number:

The official reference numbers (more complete caliber numbers) are as follows:

• NH34A11J – Made in Japan, signed JAPAN on the rotor
• NH34A11MN – Made in Malaysia*, signed MALAYSIA or no country of origin on the rotor

*It is widely assumed that modern NH movements without a country of origin are by default made in Malaysia, however, this is unconfirmed. We have contacted SII for more information about this, but they have not replied. The problem with assuming a non-Japan movement is made in Malaysia is that a movement without a country of origin can be made anywhere. With the vast number of NH movements being sold by China based trading companies (some even claiming the movements they sell are “genuine” and “made in China” within the same sentence), it is important for Seiko to address this so that the watch community can be certain where their movements are coming from. In fact, even in the official TMI tech documentation, they list two versions of the oscillating weight: Japan or Malaysia, with respective country of origin, but not mention of rotors with no country of origin. What’s going on, Seiko??

This clarification is also needed by microbrands and other non-Seiko brands using NH movements so that they are able to give accurate information to their customers about the origins of the components in the watches they produce. Sadly, some microbrand watch companies are nothing more than marketing companies that have watches designed and assembled by factories in China without actually knowing detailed technical information about the watches they advertise and sell. This is why you may come across brands that list their movements as being “made in Japan” with no country of origin on the rotor.

Seiko Only Version:

The Seiko-only version of the NH34 is the Seiko caliber 4R34 (there is a section comparing these two movements on the 6R54 caliber listing).

Examples of Watches With This Movement: