Miyota movements: 9075 GMT and 90S5 open heart
Miyota 9075 and 90S5: compare true GMT and open-heart functions, published specifications, hand winding and stop seconds for your watch project.
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Miyota 9075 and Miyota 90S5 suit different display priorities. The 9075 combines a central GMT hand with an independently adjustable local-hour hand; the 90S5 presents a three-hand open-heart view.
Published specifications: Miyota 9075 and 90S5
| Field | Miyota 9075 | Miyota 90S5 |
|---|---|---|
| Frequency | 28,800 vibrations/hour | 28,800 vibrations/hour |
| Jewels | 24 | 24 |
| Power reserve | About 42 hours | About 42 hours |
| Published factory tolerance | −10 to +30 seconds/day | −10 to +30 seconds/day |
| Measurement context | 10–60 min after full winding; dial up (Accuracy); no temperature specified. | 10–60 min after full winding; dial up (Accuracy); no temperature specified. |
| Diameter | 26.00 mm | 26.00 mm |
| Height | 4.92 mm | 3.90 mm |
| Automatic winding | Yes | Yes |
| Hand winding | Yes | Yes |
| Stop seconds | Yes | Yes |
| Date / day | Date / no day | No date / no day |
| Display function | True GMT, central GMT hand, independently adjustable hour hand | Three hands, open heart |
The tolerance figures are manufacturer values measured in the contexts shown. Case, dial, hands and movement holder still need to be selected as a complete component plan.
Miyota 9075: a local-hour adjustment for travel
MIYOTA specifies true GMT for the 9075 with a central GMT hand and an independently adjustable hour hand. The independent local-hour adjustment is useful when local time changes while the GMT hand continues to show the reference or home time. Its published functions also include a date, automatic winding, hand winding and stop seconds.
GMT MOD - PEPSI is a MedoMods GMT model using NH34. Its NH34 has an independently adjustable GMT hand, unlike the 9075's independently adjustable local-hour hand.
Miyota 90S5: an open view of the movement
MIYOTA specifies the 90S5 as a three-hand open-heart movement. The open-heart layout gives a view of the movement through the dial; the published calibre has automatic winding, hand winding and stop seconds, with no date or day display.
NAUT MOD - BLACK (OPEN HEART) is a MedoMods open-heart model using NH38. For more detail on this alternative, read the NH38 movement guide.
Select the function, then check the component plan
The 9075 and 90S5 share a published 26.00 mm diameter but have different display functions and heights. Confirm the movement holder, dial feet, hand fittings, date opening where relevant, stem, case and clearance together. For the broader 8215, 9015 and NH35 decision, read the Miyota and NH35 movement comparison.
Frequently asked questions
What does true GMT mean for Miyota 9075?
MIYOTA specifies the 9075 with a central GMT hand and an independently adjustable local-hour hand. That lets a traveller adjust local time while retaining the second-time-zone display.
Which display does Miyota 90S5 combine with an open heart?
MIYOTA specifies the 90S5 as a three-hand open-heart movement. It gives a view of the movement through the dial and has no date or day display.
Which winding and time-setting functions do Miyota 9075 and 90S5 have?
MIYOTA specifies automatic winding, hand winding and stop seconds for both the 9075 and the 90S5.
Sources
MIYOTA 9075 product page, checked 9 October 2026.
MIYOTA 90S5 product page, checked 9 October 2026.
MIYOTA 9075 specification, checked 9 October 2026.
MIYOTA 90S5 specification, checked 9 October 2026.
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