Nomos Glashütte · Nomos DUW 4101

Nomos Tangente 38 Date, Metro and Ludwig date power reserve: inside the DUW 4101

The Nomos Tangente 38 Date, Ludwig 38 Date, Metro 38 Date and Orion 38 Date run on the hand-wound DUW 4101, which lasts up to 42 hours on a full wind. That's one and three-quarter days, so it wants winding every morning you wear it.

Updated September 2026 · Based on manufacturer specs, published reviews and watchmaker/owner reports

Watches that use the DUW 4101

The DUW 4101 is the movement in Nomos's hand-wound 38 mm watches with a date. If your Nomos has a date window near the edge of the dial, a small seconds subdial and no rotor visible through the caseback, this is very likely what's inside. The no-date versions of the same families generally use the smaller Alpha, and models labelled "neomatik" are automatics with different calibers.

Nomos names the Metro 38 date and Orion 38 date as DUW 4101 models, but reference numbers vary by dial and caseback, so check the caseback or Nomos's model page for your exact watch.

Specs at a glance

History and where it came from

Nomos started in 1990 using the Swiss Peseux 7001 and switched to its own movements from 2005, beginning with the Alpha. The big step came in 2014, when Nomos introduced its own escapement, the Nomos swing system, including its own balance spring. Nomos says the press described it as "a moon landing": it meant Nomos no longer depended on Swiss suppliers for the regulating organ, which very few independent brands make themselves.

Calibers that received the swing system were renamed with the "DUW" prefix, for Deutsche Uhrenwerke. The DUW 4101 is one of them. It combines the swing system (recognisable by its tempered blue balance spring) with Nomos's patented date mechanism. Reviewers point out the key design choice: the date ring sits around the outside of the movement rather than stacked on top of it. That keeps the caliber just 2.8 mm tall and puts the date window close to the edge of the dial, which is part of why a Tangente 38 Date still looks like a Tangente.

Nomos doesn't give a launch year on the caliber's page, so we've left that out rather than guess.

Accuracy in the real world

Nomos doesn't publish a daily rate tolerance for the DUW 4101, and the standard watches aren't certified chronometers. Nomos says each movement is adjusted in six positions. For the Tangente 38 Date 175 Years editions, aBlogtoWatch reported that the movements were "adjusted to chronometer standards", but that's a claim about those limited editions rather than a certificate.

Owner reports on watch forums are generally positive, with the variation you'd expect from any mechanical watch. Hand-wound watches that are wound fully each morning spend most of the day in the strongest part of the mainspring's curve, which helps consistency. If your watch drifts more than you'd like, regulation is a routine job for a watchmaker who works on Nomos.

Reliability and servicing

With no rotor or automatic winding train, the DUW 4101 has fewer moving parts than an automatic with a date. The main extra complexity is the date mechanism.

• Brand service. Nomos offers its own servicing, the safest route while the watch is under warranty.
• Independents. Parts for the swing system and date mechanism are specific to Nomos. A capable independent can service it, but confirm they can source parts first.
• Winding. Glashütte stopwork gives a firm stop at full wind. Wind until you feel it and no further.

Quirks worth knowing

• No rotor, no top-ups. Wearing a Tangente 38 Date all day adds nothing to the reserve. All the energy comes from the crown.
• The date means resets matter. Let it stop and you'll need to set the date as well as the time. That's the real cost of a short reserve on a date watch. Follow Nomos's instructions for setting the date, and avoid changing it while the date is mid-change.
• Blue balance spring. The tempered blue hairspring you can see through the display back is the Nomos swing system, the quickest way to tell a DUW caliber from the Alpha.
• Hacking seconds. Pulling the crown stops the seconds hand, so setting to the second is easy.
• Easy to mix up. Automatic Nomos date models (neomatik) use different calibers, and hand-wound models with a power reserve indicator use another. Check before assuming yours is a DUW 4101.

How it compares

• Nomos Alpha: the smaller hand-wound Nomos with no date and 43 hours, in the Tangente 35, Club Campus and 33 mm models.
• Hamilton H-50: the hand-wound caliber in the Khaki Field Mechanical. Much plainer, no date, but 80 hours of reserve.
• ETA 6497: a big, simple hand-wound movement with about 46 hours. Far thicker and without a date.
• Powermatic 80: if what you want is a date watch that survives a weekend, an automatic with 80 hours like the Tissot PRX is the opposite approach.

Living with the 42-hour reserve

A fully wound DUW 4101 runs for about 42 hours whether it's on your wrist or not. Wind your Tangente 38 Date to the stop at 7am Monday and it will run until about 1am Wednesday. That's fine if you wear it daily and wind it each morning. It's not fine for a weekend off.

Here's the typical rotation problem. Wear your Ludwig 38 Date on Friday, wind it that morning, then switch to a diver on Saturday. By early Sunday morning it has stopped, and on Monday you're setting the time and the date. Watch Winder counts down the reserve for each watch you own and reminds you before it stops, so you can give the Nomos a wind the evening before rather than resetting a date from scratch. For a specific gap between wears, try the "Will my watch stop?" calculator.

Verdict

The DUW 4101 is a genuinely clever hand-wound movement. Nomos fitted a date and its own swing system escapement into a 2.8 mm caliber without spoiling the proportions of its classic designs. It hacks, it's adjusted in six positions and it's nicely finished. The trade-off is the 42-hour reserve on a watch with a date: miss a day and you're resetting two things. If you wear it most days and enjoy the morning wind, it's excellent. If it's one watch in a larger rotation, plan on reminders.

FAQ

How long does a Nomos Tangente 38 Date run off the wrist?

Up to 42 hours from a full wind, which is a little under two days. It's hand-wound, so it runs from the wind you gave it, whether you wear it or not.

Is the Nomos Tangente 38 Date automatic?

No. The Tangente 38 Date uses the hand-wound DUW 4101. Automatic Tangentes with a date are labelled neomatik and use different calibers.

Does the Nomos Metro 38 Date hack?

Yes. The DUW 4101 has a stop-seconds mechanism, so the seconds hand stops when you pull the crown out to set the time.

Why did my Nomos Ludwig 38 Date stop overnight?

Most likely it wasn't fully wound. Wearing it doesn't add any power, so if you didn't wind it to the stop that morning, it can stop in much less than 42 hours.

How accurate is the Nomos Orion 38 Date?

Nomos doesn't publish a rate tolerance for the DUW 4101, but each movement is adjusted in six positions. A watchmaker can regulate it if it runs noticeably fast or slow.

What is the Nomos swing system?

It's the escapement and balance spring Nomos makes in-house, introduced in 2014. In the DUW 4101 you can spot it by the tempered blue balance spring.

Do I need to reset the date if my Nomos stops?

Usually, yes. If it has been stopped past midnight, the date will be behind. Set the time and date before wearing it again.

Sources

• Nomos Glashütte: DUW 4101 caliber specifications and models
• Nomos Glashütte: the Nomos caliber range
• Monochrome: Nomos Tangente 38 Date colours, Watches and Wonders 2024
• aBlogtoWatch: Hands-on with the Nomos Tangente 38 Date 175 Years Watchmaking Glashütte

Keeping it running

• Wind it fully once a day, at the same time, until you feel the crown stop. Never force it past that point. Can you overwind it?
• A full wind lasts about 42 hours, so winding every morning keeps it running with time to spare.
• A watch winder can't wind a hand-wound movement, so it needs you instead.
• If it does stop, don't set the date between 9pm and 3am. Check if it's safe.

Never let it stop

Watch Winder counts down the reserve of every watch you own and reminds you before one stops. It already knows the Nomos DUW 4101: type your watch's name and the reserve fills itself in.

Manufacturer's published figure. Real reserve varies with the watch's age and service; check your manual.