TMI · Automatic caliber guide

NH35A

The everyday automatic.

A date display, hand winding, and a seconds hand you can stop to set the time: the NH35A covers the essentials. It is the movement behind my automatic-watch interactive, and a useful starting point for understanding what a caliber brings to a watch.

By Máté Dyékiss · Specifications checked

Explore watches using it
A study in dimensions
Ø 27.40 mm 5.32 mm
Outside diameter & movement height. Enlarged outlines, not a parts drawing.

The reference card

NH35A specifications

Published figures, with the context that makes them useful.

Movement type
Automatic mechanicalCrown hand winding and stop-seconds (hacking) supported.
Power reserve
More than 41 hTMI’s fully wound, dial-up specification.
Frequency
21,600 bph · 3 Hz6 beats each second; 3 complete balance oscillations.
Published accuracy
−20 / +40 s/dayTMI’s static rate specification under stated test conditions. Your watch’s rate on the wrist may differ.
Outside diameter
27.40 mmOutside diameter. With the dial-holding spacer, the casing diameter is 29.36 mm.
Movement height
5.32 mmMovement only. The finished watch will be thicker.
Jewels
24Jewel count is a construction detail, not a quality rating.
Display & calendar
Three central hands + dateQuickset date. Follow the watch’s setting instructions.

Specification reference: TMI — NH3 series technical guide (PDF). These are published specifications, not measurements from my own testing. All manufacturer sources ↓

My take

What I would look for

I would start here if I wanted the essential automatic-watch functions and a date, then judge the complete watch on its fit, dial, case, and price. I would not dismiss a watch because it uses an NH35, or treat the caliber name alone as proof of good timekeeping.

What it brings

  • Hand winding and hacking make starting and setting the watch straightforward.
  • A quickset calendar lets you correct the date separately from the time.
  • The same named movement connects watches from different brands.

What to weigh up

  • Its 5.32 mm movement height leaves less room for a slim case than the Miyota 90 series.
  • The published rate range is broad; do not assume a particular watch will run close to zero.
  • Six beats per second give a visibly different sweep from the eight-beat alternatives.

Beyond the spec sheet

Living with the NH35A

Starting and setting

The NH35A can be wound clockwise through the crown in its normal winding position. Pulling the crown to the time-setting position stops the seconds hand. A screw-down crown must first be unlocked; follow the finished watch’s instructions. [source]

Correcting the date

TMI says not to use the quickset date between 9 p.m. and 4 a.m. This means the time shown by the watch, including AM or PM. Move the hands outside that interval before correcting the calendar. [source]

Leaving it on the dresser

The reserve figure starts from a full wind. A short spell on your wrist does not necessarily fill the mainspring. If it stops, wind it, set the time, and check the date and AM/PM before wearing it again.

See the mechanism at workWind the crown. Follow the energy.Explore my interactive NH35A learning model.

Compare the tradeoffs

Other calibers to know

Useful comparisons for choosing a watch. These are not claims of parts compatibility.

TMI

NH34A

The NH34A adds an independently adjustable 24-hour hand for a second time zone. Both run at 3 Hz; the extra setting step is the more useful ownership distinction.

Sellita

SW200-1

Another automatic with a date, hand winding, and hacking. The SW200-1 runs at 4 Hz and has a thinner movement; its grade and the watchmaker’s regulation matter when comparing accuracy.

Miyota

9039

A different proposition for a watch without a date: 4 Hz and 3.90 mm thick. Choose between the complete watches rather than treating the 9039 as a direct replacement.

Compare all 6 calibers ↗

The movement, in a watch

Watches using the NH35A

A selected starting list, grouped by brand. Each exact model below has a manufacturer source confirming the caliber.

Links marked “affiliate” may earn me a commission at no extra cost to you. Editorial priorities come first; affiliate availability only breaks ties. It does not change my review ratings.

Sternglas

Spinnaker

Dumas Automatic Classic Black

Manufacturer-verified example

Reference SP-5081-FF

Reference SP-5081-FF specifies TMI NH35. Other Dumas models, including the GMT, use different movements.

View at Spinnaker ↗ affiliate Caliber source

Model and caliber checked October 14, 2026. Specifications and stock can change; confirm the exact reference with the seller. A manufacturer-verified example is not a hands-on review.

Quick answers

Common questions

Is NH35 the same name as NH35A?

NH35 is the shortened label commonly used on brand product pages. TMI identifies NH35A in its technical documentation. I map watches to this entry only when their exact product reference identifies the NH35, rather than assuming every Seiko-powered watch uses it.

Does an NH35A need a battery?

No. Its mainspring stores mechanical energy. The rotor winds it as you move, and the crown lets you add energy by hand. My interactive guide shows how that energy reaches the hands.

Is −20/+40 seconds per day how mine will run?

That is the movement maker’s stated static rate range, not a prediction for an individual watch. Position, state of wind, and the finished watch’s regulation affect the result. Check any separate timekeeping commitment from the watch brand.

Check the details

Sources & verification

Movement specifications checked . Watch-specific evidence is linked with each example above. I keep manufacturer claims separate from my editorial assessment and any hands-on review.

  1. TMI — NH3 series technical guide (PDF)NH35A dimensions, frequency, rate, running time, and related NH calibers.
  2. TMI — NH35 operation manual (PDF)Crown positions, clockwise winding, and the 9 p.m.–4 a.m. date-setting restriction.
  3. TMI — NH-series product lineupNH35 functions and 24-jewel specification.