Seiko Tmi Caliber Nh38a

Seiko (SII/TMI) Caliber NH38A

Seiko Tmi Caliber Nh38a

ManufacturerSeiko (SII, TMI)
Caliber NumberNH38, NH38A
Movement TypeAutomatic, self-winding mechanical
Diameter
27.40mm
Casing Diameter
29.36mm
Height
5.32mm
JewelsTwenty-Four (24)
Vibrations Per Hour
21,600 bph, 3 Hz
Lift Angle
53 degrees
Accuracy Rating
-20~+40 sec/day average
Power Reserve
~41 hours
Rotor Winding Direction
Bi-directional (Seiko Magic Lever)
Manual-Winding?
Yes
Anti-Shock SystemDiashock
Hand Count
3
FunctionsCentral hours; central minutes; central sweeping seconds
Notable Features
True no-date, open balance wheel at 9:00
Hacking Seconds?Yes
Country of ManufactureJapan/Malaysia (see below…)
Known Brands
Various Invicta, Gruppo Gamma Venturo Field III (Add your watch in the comments below…)

The Seiko caliber NH38A is a 3-hander “no-date” automatic watch movement with 24 jewels. It is a true no-date without a phantom date crown position. Many watch enthusiasts would agree that that the NH38 is the definition of a solid, no-frills workhorse movement.

The NH38 series has an open balance wheel at 9:00 on the dial side. However, many watch brands do not make use of this design feature and choose to cover it with a solid dial.

Seiko SII caliber NH38A Drawings

What is the difference between the NH38A and NH35A?

is very similar to the popular caliber NH35A in which is it based on, with the main difference being that the NH38A is essentially the no-date version of the widely used NH35A/NH36A. Unlike the NH35A, the NH38A is a basic three hand watch and does not have a day or date complication. Another difference is that the NH38A is partially skeletonized with an open balance wheel, viewable from the front side of the watch face.

Note: due to the NH35A being more ubiquitous and easy to obtain, you may find examples of watch brands offering a no-date style watch, but using the the NH35A with a datewheel instead of the NH38A. If you want a true no-date, you should not settle for an NH35A powered watch that simple has the date covered by a solid dial.

Accuracy Rating:

Time Module (TMI) claims an accuracy rating of -20~+40 seconds per day in normal operating conditions.

Japan or Malaysia or…?

The complete Japanese-made caliber number is NH38A3J. For the Malaysia variant, the official number is NH38A3M. Regardless of where the movement was made, these longer numbers are mostly for ordering purposes and not found anywhere on the movement itself. Most are not marked with a country of origin… so, technically, who knows!

Also, despite the official documentation mentioning Japan or Malaysia signed rotors, Caliber Corner has never actually seen one marked with the country of origin from the factory.

Replacement Prices:

At the time of this caliber listing, replacement prices for the NH38 were found in the range of $34.99 to $55.00 USD. You can find replacements here.

Other examples of this movement:

Below is an NH38 found in a Gruppo Gamma Field III microbrand watch:

Tmi Seiko Caliber Nh38

The large photo below is of a Seiko NH38A movement in an Invicta 22744 watch.

 

Seiko SII caliber NH38A in an Invicta watch

Image above submitted by Nathaniel B.

NH38A Tech Sheets/Technical Drawings (pdf):

Caliber Commentary:

From a post on the @calibercorner Instagram page

Additional Resources:

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Community Reviews & Questions:

  • Keep comments respectful and follow our community guidelines.
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For off topic or general watch questions, post in the Caliber Corner Forum.

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63 Comments
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Tracey Deel
Tracey Deel
7 years ago

I have this movement in an ARAGON, was Android by Wing Liang.

Jürgen Albers
Jürgen Albers
7 years ago
Doug
Doug
6 years ago

Helm Khuraburi uses the nh38a

Paul Overby
Paul Overby
3 years ago
Reply to  Doug

I have the Helm Khuraburi. So far, I am experiencing around +5 second per day with the NH38.

Joris
Joris
6 years ago
Zoroff
Zoroff
6 years ago

Armourlite also uses NH38

Will
Will
6 years ago

I have this watch in a Momentum Morioka watch.

Bert
Bert
6 years ago
Reply to  Charles Laigo

My Phoibos Wavemaster is a great watch but the Seiko movement in it is at least 10 seconds a day slow, a common issue. I wish brands would regulate these movements before shipping!

Rich
Rich
5 years ago

My Giorgio Fedon has this movement.

W
W
5 years ago

Traska Freediver

Øyvind
Øyvind
5 years ago

Used by Giorgi Fedon 1919

Roger Ingram
Roger Ingram
5 years ago

Also found in Traska watches

Jeff Summers
Jeff Summers
3 years ago
Reply to  Roger Ingram

Hey I am a huge fan of yours. Had one of your Jupiter trumpets for years. You should check out my YouTube channel at https://www.youtube.com/channel/UCnGYxMEr5niyVeTjduwLBpw
Awesome you are a watch fan too!!

Best,
Jeff Sumners

koimaster
koimaster
5 years ago

I love coming to this site to learn more about movements and to share.

Brian Centeno
Brian Centeno
2 years ago
Reply to  calibercorner

I too enjoy the heck out of this site. Is there any chance that some of the Chinese GMT and higher beat rate movements such as the Hangzhou 6460 can be included? I see the PT5000 here. Great information!!!

Brett
Brett
2 years ago
Reply to  koimaster

Me too. Now I learned to better appreciate watches more for their movement than their looks. I love coming to this site. I learn something new every time.

Rudy
Rudy
5 years ago

There is a typo in the table box.
Malaysia not Maylasia. 🙂

Remco
Remco
4 years ago

This movement is also used in the limited edition TW Steel’s Son of Time MST6.

evansna
evansna
3 years ago

Aquacy Cave Diver uses as well

E.A. Po
E.A. Po
7 months ago
Reply to  evansna

Just got a used one from Ebay. Like it so far- enjoying the beating of that [hideous]heart!

IMG20231219100355
trackback
Vario Empire Tuxedo – White & Gold – Beans & Bezels
3 years ago

[…] doesn’t work for you, you can also look at the automatic variant of this model that houses a Seiko NH38A. This comes at the cost of an additional 0.5mm of case thickness. In my opinion, the hand-wound […]

GreyMisha
GreyMisha
3 years ago

My invicta Master of the oceans uses this Caliber too. Very useful webpage. Thanks

Chris
Chris
3 years ago

In Zum watch R1
(In kikstarter actually)

justin hanson
justin hanson
3 years ago

vario is also using this movement

trackback
RZE Endeavour – Beans & Bezels
3 years ago

[…] watch uses a Seiko NH38A movement, so no date complication or a ghost date position. For the price, and given the […]

Áron
Áron
3 years ago

Villandry uses NH38. They say.

trackback
Presentación Vanbanner Parkingmaster - SaFonaGastroCrono
3 years ago

[…] motor del Parkingmaster no es el Roadster 2.0 de Tesla, sino el práctico NH38, primo sin fecha del ubicuo NH35. Al igual que el NH35, se trata de un calibre que oscila a 21.600 […]

Alister Hill
Alister Hill
3 years ago

Wearing a Reign ‘Bauer’ that arrived today, with this movement (so the website says). No prizes for guessing that I didn’t pay the MSRP for it! It is a nice watch, though.

https://reignwatches.com/products/reirn6000?variant=35116922208423

Stefan Vos Carrasco
Stefan Vos Carrasco
3 years ago

Ví este movimiento en un reloj Megir.

trackback
Presentación Vario 1918 Trench Watch - SaFonaGastroCrono
3 years ago

[…] con este ejemplar. Las versiones “Medic” equipan el calibre automático SEIKO NH38A, una versión sin fecha del archiconocido calibre […]

Glenn Williams
Glenn Williams
3 years ago

Cincinnati Watch Company “Cincinnatus” field watch.

Zio
Zio
2 years ago

I have it in the Aerotec ACE

Skidpalace
Skidpalace
2 years ago

Is this movement compatible with cases made for NH35/36, such as SKXs and the like?

José Carvalho
José Carvalho
2 years ago

I guess I am lucky… Extraordinary movement!
I have several higher end automatic movements (including Swiss!) and by far this is the most accurate one, about 20 seconds (+) per month!
I have it in a Briston Clubmaster Iconic Automatic and it is now my daily watch!
I am truly amazed how accurate it is!!!

craig
craig
2 years ago

is the NH38 handwinding. and is there any major disadvantages to having the malaysian movement?

Brett
Brett
2 years ago
Reply to  craig

Read the page. Yes, it’s hand winding. I have a Malaysia made with a date and it’s great. It’s the same movement just made in another place.

JohnM
JohnM
10 months ago
Reply to  Brett

more accurately, it’s an automatic movement with hacking i.e. you have the option to hand-wind the movement as well, usually with the crown at 1st click out.

JohnM
JohnM
10 months ago
Reply to  JohnM

Hï – this comment by me needs clarification. I tried editing the original comment but I couldn’t – I assume to defeat robots bombarding the site. Hacking and hand-winding are two different attributes, and the NH38 has both.

Roy Benny
Roy Benny
2 years ago

I just saw a brand of racing watches called ZUM that uses this movement as a regulator watch.

trackback
Presentación Nodus Sector Dive - SaFonaGastroCrono
2 years ago

[…] no es un reloj ostentoso, ni su movimiento. Batiendo a 21.600 vph (3 Hz), lo impulsa un SEIKO NH38 automático. Esta versión sin fecha significa que no hay posición fantasma en la corona. También […]

Dirk
Dirk
2 years ago

Bering mentions on their website that the movement of a BERING Vitus 1728 has been developped with Miyota, still this watch has the NH38A (SII) in it

Chris
Chris
2 years ago
Reply to  Dirk

Same with a Bering 16743-307 watch I own. The Vitus 1728 is the Miyota movement they are referring to. Looks like they chose a better movement with the NH38A. They just need to update the website. -1 second per day for mine. I love it.

trackback
Presentación Namica Shirahama Dive Watch - SaFonaGastroCrono
2 years ago

[…] Shirahama equipa el calibre SEIKO NH38. Se trata de la versión sin fecha del popular NH35, un verdadero “caballo de batalla” […]

William Waddell
William Waddell
2 years ago

Islander Watch #ISL-82 uses this caliber.

trackback
Proyecto Flieger Económico - SaFonaGastroCrono
2 years ago

[…] este caso recurrí a eBay para adquirir un NH38A de SEIKO por €47 (con envío desde la UE). Debo remarcar que el precio de los calibres de la […]

trackback
3 Лучших Механических Часов из Дерева (2022) — Wrist Watch Everywhere
2 years ago

[…] Внутри часов находится японский часовой механизм Seiko NH38-3, 24 искусственных драгоценных камня, а также пружина с запасом хода в 41 час (источник). […]

Sergio Luiz Sant Anna
Sergio Luiz Sant Anna
2 years ago

Züm Watches is announcing an automotive-themed regulator. The self-winding rotor has design of a race car steering wheel.

121090823_3301542763298649_7284744307459143351_n.jpg
Alex
Alex
2 years ago

Addiesdive AD2103

Magnus Axelsson
Magnus Axelsson
1 year ago

The RZE Valour 38 uses this movement.

Matt
Matt
1 year ago

niwatch mikro brand from Poland that makes “wooden watches” using the NH38-3 skeletal version.
https://niwatch.pl/zegarek-niwatch-automatic-drewno-chacate-preto

J.C.
J.C.
1 year ago

Aquacy Watches also uses the NH38 in its “Cave Diver” model. It’s a solid enough movement, as long as you are not too obsessive about accuracy. Average variance is somewhere around +15 to +20 seconds per day, in my personal experience. I haven’t seen one that runs slow yet. Doesn’t mean they don’t exist, though.

Jeremiah B Leonard
Member
1 year ago

Can anyone say if this movement can be swapped out in a watch which normally comes with it? Specifically, I would like to replace the NH38 in my Khuraburi with something more special. Is there a movement that is the same but a higher quality? Maybe a chronometer grade!

Nino Barragán
Nino Barragán
9 months ago

El mío es un Giorgio Fedom. Lleva el NH38A. Me encantan los relojes. Intento hacer una colección dentro de mis posibilidades

16966994599159158570451713255169.jpg
Hash Bob
Hash Bob
8 months ago

Vince Camuto uses this movement.

Andrew Pullens
Andrew Pullens
8 months ago

Does anyone know the lift angle on the NH38A? 53 degrees like the NH35?

Patrick McDonagh
Patrick McDonagh
7 months ago

I compare all automatic movements with Seiko SR15.
How would you compare that with NH38 ?

Joshua
Joshua
7 months ago

Boldr Voyage uses this movement too! I haven’t noticed that drastic of a time change, but I’ve also only had it for 6 months.

Krishang Gor
Krishang Gor
3 months ago

I own a watch from Titan a classic Indian watch brand and it uses a NH38a movement . Pretty pleased with my timepiece yet 🙂

J.B. Reese
J.B. Reese
2 months ago

I have an Islander Watch #ISL-169 with an NH38 Movement. It mentions it at the bottom of the dial as well. Their dressy dive watch series which will likely be sunsetted this year.

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