Seiko Tmi Nh Caliber

Seiko Caliber NHxx Variation Differences

Seiko Tmi Nh Caliber

What is the difference between Seiko/TMI/SII “NH” calibers?

As of this post there are 10 calibers in the current line of NH “Basic Mechanical Series” movements. We will focus on the main 6 variations based on the NH35, information about the other four will be at the bottom of the page.

Mens size watches

There are some differences between these overall similar movements but they are all based off of the original NH35 caliber which is based off of the NH25. The differences are mostly related to day/date/24 hour indicator. Please compare in the chart below. Did we miss anything? Please comment below.

Main Differences:

NH35ANH36ANH37ANH38ANH39ANH70A
3 HandsYesYesYesYesYesYes
DateYesYesYesNoNoNo
DayNoYesNoNoNoNo
24 Hr DialNoNoYesNoYesNo
SkeletonNoNoNoNoNoYes

Specs Comparison:

NH35ANH36ANH37ANH38ANH39ANH70A
OriginJapan/Malaysia
Year Introduced2011?Unknown UnknownUnknown Unknown 2017
Diameter12”’ (27.40mm)
Casing Diameter29.36mm 27mm
Height5.32mm
Jewels24
Power Reserve> 41 Hours
Beats Per Hour21,600 vph (6 vibrations per second)
Lift Angle53 degrees
Hacking?Yes
Hand-Windable?Yes
Winding Direction?Bi-directional
Shock-Absorber
Seiko Diashock
COSC?No

Accuracy

Time Module claims that the NH calibers are rated for static accuracy of -20 ~ +40 under normal temperature conditions. All measurements are done without the calendar function, as well as within 10-60 minutes while fully wound.

Difference Between Crown Functions

As we see here, the main differences between the two calibers is that the NH35A is hackable and can be hand-wound. That means the crown operates differently:

 Crown PositionNH35ANH36ANH37ANH38ANH39ANH70A
0

Clockwise: Manual Winding

Counterclockwise: Free (does nothing)

1
Clockwise: Nothing

Counterclockwise: Sets the date (quick set)

Clockwise: Sets the day

Counterclockwise: Sets the date (quick set)

Clockwise: Nothing

Counterclockwise: Sets the date (quick set)

Time SettingTime SettingTime Setting
2
Time SettingNoneNoneNone

Which NH caliber movement does my watch have?

Unless the manufacturer installed a custom rotor, the caliber number should be engraved or stamped there. If it has a closed caseback or custom rotor, you can tell by looking at the complications on the dial. Of course, it’s always possible that the manufacturer made their own modifications or removed some features that didn’t correspond with the watch design (say for example they got a really good deal on 200 NH35A but the watch doesn’t have a date window, they could just use the NH35A without the date).

Which one better?

It really depends on what you need from a watch! If you like simple minimalist 3 hand watches, then the NH38A is for you. If you like have a 24 hour subdial, then go for a watch with the NH37A. Let the community know which caliber you prefer and why in the comments below…

Ladies and midsize NH calibers:

  • NH05
  • NH06
  • NH15
  • NH16

NH VS NE:

TMI aka Seiko Instruments markets the “NH” calibers as “Basic” Mechanical Series. They also have “NE” calibers that are marketed as “Premium” Mechanical Series.

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2 years ago

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Wes Nicholson
Wes Nicholson
1 year ago

HI! I have a modded 7s26. It gains 15mins per day when worn, but maybe 2mins per day when not worn. I want/need a more accurate movement. I don’t have “day”, “date” or “24hr” requirements. Just the 3 hands and accuracy are required. What do you recommend would fit? Will the NH70 fit? Thanks

Naumann
Naumann
1 year ago
Reply to  Wes Nicholson

the NH70 is on point accurate since a week. Now i am looking at my laptops time. its says 10:13 and my NH70A caliber shows me 10:13. Last time i adjusted the time, was when i bought it, 2 weeks ago. So accuracy …nailed it!

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mark wolfson
mark wolfson
1 year ago

My Invite Pro Diver 8926OB has the NH35A just purchased August 2019. However, it functions differently than described above. First, when pulled out to ‘zero,’ it feels free with no feel of any attachment of crown moving the winding p Iart of movement. Am I winding, going clockwise with no feel of friction? Next, the watch does not stop when crown pulled out to 2nd click. So hacking (synchronizing second hand to minutes hand at… Read more »

Eddie M.
Eddie M.
1 year ago
Reply to  mark wolfson

Maybe you can try posting this on the NH35A thread and see what they say over there. Do a search.

Tom
Tom
7 months ago
Reply to  mark wolfson

Are you sure your watch really has the NH35A? I may be wrong but from what you describe, it seems you have the NH25A instead. More explaination here: https://calibercorner.com/seiko-caliber-nh25a-vs-nh35a/

D
D
6 months ago
Reply to  mark wolfson

Zero = not pulled out, which will wind clockwise, 1= date change, 2=time setting and seconds stop.

mark wolfson
mark wolfson
1 year ago

Sorry it is an Invicta, not Invite, sorry for auto spell

Renaldo Valentin
Renaldo Valentin
6 months ago

I own an Invicta Grand Diver w/ the Seiko NH35a & currently it is -14 seconds a day, Generally I’ve owned many eta movements that ran +12 seconds a day. At first the time factor +/- a day didn’t bother me. Though as I continued collecting autos that became unacceptable for my liking. So I’d either sell the watch or sent it directly to the manufacturer for adjusting. So currently I have no watches +/-… Read more »

JAEE
JAEE
5 months ago

What’s the difference between NH35A (vs) NH70 ?
And which one is better? And why?

Phas
Phas
5 months ago
Reply to  JAEE

Did you not see the charts above?? The 70 is a skeleton dial.

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Szosky Miki
Szosky Miki
26 days ago

There’s some conflicting info here – you’ve stated that manual winding is bi-directional, then go on to say it’s in the clockwise direction only. Is it in both directions?

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