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 is 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.


You are reading Caliber Corner, the most popular resource for watch movement pics, specs, mods and DIY repairs. Follow @calibercorner on Twitter, Instagram but NOT Facebook. Subscribe on the YouTube. Join our mission to spread movement awareness (currently invitation only while beta testing, check back for sign-up link).
What do you think about Seiko Caliber NHxx Variation Differences? Keep comments respectful and follow our community guidelines.
Subscribe
Notify of
guest

43 Comments
oldest
newest most voted
Inline Feedbacks
View all comments
trackback
Seiko (SII) Caliber NH37A Watch Movement | CaliberCorner.com
5 years ago

[…] Also see this thread: Seiko NH Caliber Comparison/Differences […]

trackback
Seiko (SII) Caliber NH35A Watch Movement | CaliberCorner.com
5 years ago

[…] Also read: Seiko NH Caliber Comparison/Differences […]

trackback
California Dial on Smaller Watches? - Page 2
4 years ago

[…] this watch should be using an NH38A (3 hands only), instead of one with a Day/Date movement ??? Seiko Caliber NHxx Variation Differences Watch Movement | CaliberCorner.com Anyway, nice watch, just easily $1000 too much. cheers Reply With […]

trackback
Invicta Diver Pro - Page 2
4 years ago

[…] and the NH36 are the same. The 4R35 and the NH35 are the same, and so on. More information here: Seiko Caliber NHxx Variation Differences References From WUS Members: KeepTheTime are fabulous | KeepTheTime is a great […]

trackback
Mechanical Watch differences - designer fashion products
4 years ago

[…] Seiko Caliber NHxx Variation Differences Watch Movement … […]

trackback
differences Mechanical Watch Skeleton - designer fashion products
4 years ago

[…] Seiko Caliber NHxx Variation Differences Watch Movement … […]

trackback
SNZH55 movement swap
4 years ago

[…] think the only difference btween the NH35 & 36 is day wheelSeiko Caliber NHxx Variation Differences Watch Movement | CaliberCorner.com Most stems can be unscrewed from the crown, might be worth checking that out before you try and buy […]

Wes Nicholson
Wes Nicholson
3 years 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
3 years 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!

Luis Mirantes
Luis Mirantes
1 year ago
Reply to  Naumann

will the nh70 fit an skx007 case?

HoustonReal
HoustonReal
1 year ago
Reply to  Luis Mirantes

Probably, but you’d want the NH36A/4R36, to replace your 7S26. The NH36A is slightly thicker, but many others have performed this mod, along with a sapphire crystal, and a ceramic bezel transplant.

There are mod kits that come with a modified caseback to accommodate the extra thickness of the movements, and plenty of blogs and YouTube videos documenting the change.

alfred klek
alfred klek
1 year ago
Reply to  HoustonReal

15 minutes a day is a lot. I’d say it’s either not regulated properly or needs service depending on it’s age. My 7s26 loses 3 seconds a day pretty consistently. The reason I’m reading up on the newer movement is that I’d like a hack and handwind. If that’s not important to you, a 7s26 can run really well

Ed
Ed
9 months ago
Reply to  alfred klek

They all want detailed descriptions of your timepiece to work. It’s like filling in a tax return. I tried 3 of them, they’re all convoluted in one way or another.

Mike Robinson
Mike Robinson
1 year ago
Reply to  Wes Nicholson

Have tried adjusting it the movement? It should be +/- 20 sec per day. My own 7s26 was adjusted to around +2 sec. Using a phone app like “Watch accuracy meter” allows you to check adjustments without waiting all day.

Todd Denzer
Todd Denzer
1 year ago
Reply to  Mike Robinson

Congrats on adjusting to such perfection! Is it still consistent or has it changed at all?

Mike Robinson
Mike Robinson
7 months ago
Reply to  Todd Denzer

Sadly it stopped working altogether. I was snorkelling out in Greece and suddenly noticed dampness on the back of the dial. The stem gasket had gone and water had got into the movement. I ended up sending it back to Seiko who replaced the movement, gaskets and stem/crown. They charged me £125 which I think was good value. I haven’t tested the watch for accuracy but I suspect it’s not as good as before.

pus2meong
pus2meong
7 months ago
Reply to  Mike Robinson

I got my watch -4 sec with the app.
I will just be satisfied with this value.

BocaSlim
BocaSlim
1 year ago
Reply to  Wes Nicholson

Don’t switch out the movement; instead, just have the one you have cleaned and serviced.

trackback
Seiko Magic Lever Watch Movement | CaliberCorner.com
3 years ago

[…] Lever system referred to as the Pawl Lever. For example, the official Seiko tech sheets for the caliber NH3 series lists this as part 0831 […]

mark wolfson
mark wolfson
3 years 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.
3 years 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
2 years 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
2 years 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
3 years ago

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

Renaldo Valentin
Renaldo Valentin
2 years 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
2 years ago

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

Phas
Phas
2 years ago
Reply to  JAEE

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

trackback
D1 Milano Skeleton Automatic (Castellano) – SaFonaGastroCrono
2 years ago

[…] corona octogonal opera el calibre SEIKO NH70A, una versión altamente esqueletonizada, sin fechador, de la familia del NH35, es decir la versión […]

trackback
D1 Milano Skeleton Automatic (English) – SaFonaGastroCrono
2 years ago

[…] octagonal crown operates the SEIKO NH70A caliber, a heavily skeletonized dateless version of the NH35 family, i.e. the NH38A in this […]

Szosky Miki
Szosky Miki
2 years 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?

trackback
Seiko (SII) Caliber NH35A Watch Movement | Caliber Corner
2 years ago

[…] It’s also important to note that the Seiko NH35A movement is basically an unbranded version of the Seiko caliber 4R35. for example, the NH36 is an unbranded version of the 4R36 (day + date) found in the Next Generation Orange Monster. Read: NHXX caliber differences. […]

Ulrich Sido
Ulrich Sido
2 years ago

Ich habe eine Invicta Pro DIVER mit Nh35a,die läuft besser als viele R…,O…,sage und schreibe max 15Sek/Woche.Wenn ich es nicht selbst vor Augen hätte,dann würde ich es aus Erzählungen,von Anderen nicht glauben.Es es ist die Wahrheit,das “billige”,Uhrwerk,nimmt es gut eingergelt locker mit einem 2824 ETA auf.

Taylan
Taylan
1 year ago

4r37a is very accurate. I calculated my ssa381k seiko watch for 21 days so far and it has +1 seconds per day accuracy. I love seikos, they are rather cheap, accurate and durable.

Taylan
Taylan
1 year ago
Reply to  Taylan

pardon it is 383k1 actually. and I wear it all the day.

trackback
Seiko 4R Watch Movement | Caliber Corner
11 months ago

[…] Seiko caliber 4RXX family of automatic movements is basically Seiko’s branded versions of the SII NH family. These are the movements that Seiko uses in their own watches. The NHXX equivalents are sold to […]

Zeke
Zeke
9 months ago

Very helpful.

Mohamed Essam
Mohamed Essam
6 months ago

Is it legal to use the NH35 in micro brands?

Leo
Leo
5 months ago

Does anyone have any experience with the Seiko NH16 movement? Is it accurate? Reliable? Thank you for your time.

James
James
5 months ago

You can adjust the time gain or lose. You see on the movement next to the balance wheel a plus and minus sign with a screw that screw will add it subtract time making it run faster or slower but be careful the tiniest turn of the screw can make several seconds difference

Mark Owen-Greene
Mark Owen-Greene
15 days ago

Anyone know if the NH38 uses the same balance wheel/splint config as the NH 35-36- etc?
I need some and cannot find them anywhere.

;
Venus Caliber 178
43
0
Would love your thoughts, please comment.x
()
x