Sii Caliber Ne15b

SII (Seiko Instruments) Caliber NE15B

Sii Caliber Ne15b

ManufacturerSeiko Instruments (SII)
Caliber NumberNE15B
Base Caliber
Movement TypeAutomatic
Casing Diameter
Vibrations Per Hour
21,600 bph
Lift Angle
53 degrees
Power Reserve
~50 hours
Hand Windable?Yes
Winding Direction
Rotor Speed Rate
30 rpm
Anti-Shock System
Seiko Diashock
Regulator System
Hand Sizes
1.50mm / .89mm / .21mm
FunctionsHours, minutes, central seconds, date calendar at 3:00
Country of ManufactureJapan
Known Models
Minus-8 Diver (Add yours in the comments below…)

The Seiko caliber NE15B is a movement produced by Seiko Watch Corp. in their Seiko Instruments branch. This movement was released circa . It is an automatic movement with a ball bearing rotor.

Caliber NE15 VS NE15B:

The B at the end of NE15B indicates an evolution of the NE15 (NE15A). The official tech sheets for the caliber NE15B were updated on September 16, 2014. According to this post, the major upgrades included:

  • Add one jewel on main plate, barrel hole
  • Modify ratchet sliding spring
  • Modify date indicator maintenance plate
  • New balance wheel
  • New barrel

Caliber 6R15C VS SII NE15B:

The caliber 6R15C is basically a Seiko-only version of the NE15B. Seiko Instruments (aka SII) sells the NE15B to other manufacturers (such as microbrands) for use in non-Seiko watches. Note: apparently some early versions of the 6R15C only have 23 jewels compared to the newer ones with 24J (the NE15B has 24).

Accuracy Rating:

Seiko claims that the accuracy of caliber NE15B is between -15/+25 seconds per day. This rating is based on normal daily wear on the wrist in normal operating temperatures. When testing your watch for timekeeping, make sure it is fully wound.

Power Reserve:

The caliber NE15B holds a power reserve of greater than 50 hours. To fully wind the mainspring, turn the crown a minimum of 55 times.

Crown Position Functions:

0 (against the case): Clockwise = Manual Winding / Counterclockwise = Nothing
1 (pulled out one click): Clockwise = Nothing / 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:

Seiko Caliber 4r36 Stem Removal

Replacement Price:

At the time of this post, replacement movements were found online for $115.00 USD.

Examples of Watches With This Movement:

The photos in this post are of an SII caliber NE15B found in this Minus-8 Diver:

Seiko Sii Caliber Ne15b Minus 8

Additional Resources:

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3 years ago

My friend has a broken Seiko watch with a 6r15 will this one work as a replacement?

2 years ago
Reply to  Mel

Any 6R15 is dimensionally the same as an NE15. I myself replaced a horrible 6R15D in my SARB017, which turned out to have a very low amplitude of 170°, with an NE15B. Runs -3 spd consistently at 290° fully wound. My experience with over a dozen of them in myh collection is that SII movements somehow always turn out to be far more reliable than Seiko ones. I might just be unlucky.

2 years ago
Reply to  Mel

Yes, but I wouid try taking your 6r15 to a watchmaker first to see if the movement cannot be repaired. I had a poorly performing 6r15D that was serviced by a matchmaker and is now performing to COSC.

2 years ago, uses this movement (They Specify use of the “SII NE15C”, even though the article states it’s a “Seiko only” version of the movement) in their Atlas, a limited run of their premier “operators” watch, created for ”for those who work in dynamic environments”. I can verify, personally, that the movement as currently calibrated does lose approximately 15 sec/day according to

2 years ago
Reply to  Ron

You read it backwards. 6R15 is the “Seiko only” version of the NE15. Meaning the NE15 is used in watches like what you mentioned, but the 6R15 is used in Seikos only.

Venus Caliber 178
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