The main difference between the NH35 and NH36 is the display. The NH35 shows the date, while the NH36 shows both the day and date. Both are automatic mechanical movements with 24 jewels, a beat rate of 21,600 vibrations per hour, around 41 hours of power reserve, and a manufacturer accuracy range of -20 to +40 seconds per day.

The NH35 and NH36 are two of the most widely used automatic movements in the Seiko mod market. Both movements are popular with watch builders and micro-brands because they offer reliable performance, manual winding, hacking seconds, and a practical automatic winding system. 

So, which movement should you choose? Let’s find out.

What Are the NH35 and NH36 Movements?

The NH35 and NH36 are automatic mechanical watch movements manufactured by Time Module Inc. (TMI), a subsidiary of Seiko Instruments Inc. They are widely used in Seiko mod watches and are also found in watches from various micro-brands.

Both movements are designed to wind automatically as you wear the watch. The movement uses the motion of your wrist to wind the mainspring and store energy. When fully wound, both the NH35 and NH36 provide approximately 41 hours of power reserve.

Both movements also support manual winding and hacking seconds. Manual winding allows you to wind the movement directly through the crown, while hacking stops the seconds hand when the crown is pulled into the appropriate position. This makes it easier to set the watch accurately.

At Chrono Customs, we build our watches with genuine TMI movements and test each movement for accuracy before the watch is shipped.

Our experience building Seiko mod watches gives us a practical perspective on how the NH35 performs in everyday use.

The Core Difference: Date vs. Day-Date

The biggest difference between the NH35 and NH36 is the calendar display.

The NH35 is a date-only movement, meaning it is designed to display the numerical date through a single date window on the dial. This layout works particularly well with watches that have a clean, minimalist, dive-style, or traditional dress-watch design.

The NH36 is a day-date movement, meaning it displays both the numerical date and the day of the week. This requires a different dial layout because the dial needs to accommodate both calendar displays.

In practical terms, the difference is simple: the NH35 gives you the date, while the NH36 gives you the day and date. Their core timekeeping performance is otherwise very similar.

Full Specification Comparison between NH35 and NH36: 

The following table compares the key specifications of the two movements. Have a look - 

The specifications show why the choice between the NH35 and NH36 is usually more about the dial and calendar display than about performance. 

Both movements offer the same beat rate, a similar power reserve, the same number of jewels, and the same stated accuracy range.

Does the Difference Between NH35 and NH36 Matter?

For most watch buyers, the difference matters mainly because of the type of display they want. If you prefer a simple date window and a cleaner dial, the NH35 is usually the better choice.

If you regularly use the day-of-the-week display and prefer having more information on your wrist, the NH36 may be more suitable.

Neither movement should be viewed as a major performance upgrade over the other. The NH36 does not automatically keep better time than the NH35, and choosing the NH35 does not mean sacrificing power reserve or basic mechanical functions.

When the NH35 Makes More Sense

The NH35 makes sense when your priority is a clean and straightforward dial. Because it uses a single date display, it works well with many dive-style, field-style, minimalist, and dress-style watch designs.

The simpler calendar layout can also make it easier to match the movement with different dial designs. If you do not regularly need to know the day of the week from your watch, the additional day display offered by the NH36 may not provide much practical benefit.

For buyers who simply want a reliable automatic movement with a date function, the NH35 provides everything they generally need.

When the NH36 Makes More Sense

The NH36 is a better fit if you want both the day and date displayed on your watch. A day-date display can be particularly useful for everyday wear, especially if you frequently need to check the day of the week while working or managing your schedule.

The day-date configuration is also associated with many classic watch designs. If you specifically like the appearance of a day-date dial, choosing the NH36 allows you to build the watch around that layout.

The important point is that you should choose the NH36 because you want its day-date functionality, rather than because you expect it to offer better timekeeping performance.

Understand the NH36 Day-Setting Function

One detail that can confuse first-time NH36 buyers is the way the day display is adjusted.

The NH36 has a day and date calendar system, but the exact day-setting operation can depend on the movement configuration and crown position.

In many NH36 setups, the day and date are adjusted through different crown positions. The day display can also be advanced through the movement's calendar mechanism.

Because watch configurations can vary, it is best to follow the instructions provided with your specific watch rather than assuming that every NH36 build operates in exactly the same way.

As a general precaution, avoid changing the calendar functions while the movement is in the middle of its automatic date-change period. Doing so can place unnecessary stress on the calendar mechanism.

Why Chrono Customs Uses the NH35

Chrono Customs uses genuine NH35 movements across its watch builds because the movement fits the design philosophy of our collections.

The NH35 provides a clean single-date display while delivering the automatic winding, manual winding, hacking seconds, and accuracy characteristics expected from this type of movement.

The date-only configuration also gives our designs a simpler dial layout. This is particularly useful for watch styles where a clean dial is an important part of the overall appearance.

Another advantage is consistency. Since the NH35 and NH36 have the same stated manufacturer accuracy range, choosing the NH35 does not mean giving up timekeeping performance simply because the watch does not have a day display.

Each Chrono Customs watch is assembled and tested before shipping, helping ensure that the movement is functioning correctly when it reaches the customer.

Common Mistakes Buyers Make

One common mistake is assuming that the NH36 automatically keeps better time than the NH35 because it is the higher-numbered movement.

The number does not mean that the NH36 is a performance upgrade over the NH35. Both movements have the same stated manufacturer accuracy range and similar core specifications.

Another mistake is choosing an NH36 without considering the dial. The NH36 requires a day-date-compatible dial, so the movement and dial need to be designed to work together.

If you prefer a traditional date-only dial, the NH35 is generally the more appropriate choice.

Buyers should also avoid selecting a movement before deciding on the overall watch design. The dial, calendar display, case, and movement need to be compatible.

Choosing the desired dial style first can make the movement decision much easier.

Finally, pay attention to the source of the movement. When purchasing a Seiko mod, check whether the seller clearly identifies the movement manufacturer as TMI rather than simply describing it as a generic automatic movement.

How to Care for an NH35 or NH36 Watch

The NH35 and NH36 require similar basic care because both are automatic mechanical movements. Regular wear allows the rotor to wind the movement naturally, while manual winding can be used when additional power is needed.

Mechanical watches should also be protected from strong magnetic fields because magnetism can affect the movement's accuracy.

If you notice a sudden and significant change in timekeeping, magnetization is one possible cause.

For long-term maintenance, mechanical movements should be inspected and serviced periodically. A commonly suggested interval is around three to five years, although the appropriate service schedule can vary depending on how frequently the watch is worn and its operating conditions.

When using the calendar function, avoid manually changing the date or day during the movement's calendar-change period, typically around the late-evening to early-morning hours.

This helps reduce the risk of damaging the calendar mechanism.

Frequently Asked Questions

Q. Is the NH36 more expensive than the NH35?

The NH36 is generally slightly more expensive than the NH35 because it includes the additional day-display functionality. However, the price difference is usually relatively small and can vary depending on the seller, watch build, dial, and other components.

Q. Can I upgrade an NH35 watch to an NH36 later?

An NH35-to-NH36 conversion may be possible, but it depends on the case, dial, movement configuration, and other components used in the watch. Because the NH36 uses a day-date display, a compatible dial is normally required. A qualified watchmaker should check the watch before attempting the conversion.

Q. Which movement keeps better time, NH35 or NH36?

Neither movement is inherently more accurate than the other based on the manufacturer's stated specifications. Both the NH35 and NH36 have a stated accuracy range of approximately -20 to +40 seconds per day. Actual performance can vary between individual movements and depends on factors such as regulation, wear, position, and operating conditions.

Q. Does Chrono Customs use the NH35 or NH36?

Chrono Customs builds its watches with genuine NH35 movements. The NH35 is used because its date-only configuration fits the clean dial designs used across our collections while providing the automatic and mechanical functions our watches require.

NH35 vs. NH36 - Which One Should You Choose?

The choice between the NH35 and NH36 is straightforward once you focus on the feature that separates them.

Choose the NH35 if you want a date-only display, a cleaner dial, and a straightforward automatic movement. Choose the NH36 if you specifically want both the day and date displayed on your watch.

In terms of core performance, there is no major reason to choose one over the other. Both movements have 24 jewels and a 21,600 vibrations-per-hour beat rate.

Both have approximately 41 hours of power reserve, manual winding, hacking seconds, and a stated accuracy range of -20 to +40 seconds per day.

For most Seiko mod buyers, the decision ultimately comes down to dial design and calendar functionality rather than timekeeping performance.

Ready to Choose Your Movement?

You now know the real difference between the NH35 and NH36: one date window versus two, and nothing more on the performance side.

Chrono Customs builds every watch with a genuine, tested NH35 movement and a clean, single-date dial. Browse our collections to see the movement in action, or contact our team with any questions about your first purchase.