The Miyota 8N24 is a widely used open-heart / skeleton automatic movement produced by Citizen’s Miyota division in Japan. Known for its reliability, smooth winding performance, and visually striking skeletonized structure, the 8N24 is popular in both microbrand and custom watch builds. Its stable accuracy, robust architecture, and attractive display make it a favorite for dress watches and transparent designs.

Miyota 8N24 – Detailed Specifications

Basic Info

• Type: Automatic (self-winding)

• Origin: Japan (Citizen / Miyota)

• Display Style: Skeleton / Open-heart movement

Performance

• Accuracy: approx. −20 to +40 seconds/day (factory standard)

• Power Reserve: ~42 hours

• Beats / Frequency: 21,600 vibrations per hour (3Hz)

• Jewels: 21 jewels

Functions

• Time-only display: Hours, Minutes, Seconds

• No date complication

• Hacking: No

• Hand-winding: Yes

Dimensions

• Diameter: 26.0 mm

• Thickness: 5.3 mm

• Hand Sizes:

  • Hour: 1.5 mm

  • Minute: 0.9 mm

  • Second: 0.2 mm

Other Features

• Skeletonized plates and bridges for transparent dial or exhibition caseback designs

• Rotor: Decorated, bi-directional winding

• Durability: Known for shock resistance and long-term stability