perpetual calendar

Overview

A perpetual calendar watch accounts for leap years and displays the correct date until the year 2100. Conventional perpetual calendar functions are executed in levers and springs, are delicate to handle, and comprise numerous parts (Patek Philippe uses 182). The date is usually only adjustable in one direction via pushers on the sides of the case.

Ludwig Oechslin

Dr. Ludwig Oechslin’s perpetual calendar watch is designed to be practical  –  from its unique date display to the simplicity with which it can be set. As he explains in this video, the date is displayed with analog dots so that it can be read from further away than with numerical indications, and to keep the time the first information in the watch’s visual hierarchy. Dr. Oechslin’s perpetual calendar function is executed in just 9 additional parts, because fewer parts mean fewer interactions between parts and higher reliability. The date is adjustable both forwards and backwards, and every function can be set simply using the crown.

The interactive watch below shows how to read the functions, and you can learn about how the function works in the “Mechanics” section. Detailed technical information is available at the bottom of this page.

Your perpetual calendar watch

ochs und junior manufactures about 15 perpetual calendar watches per year. Each watch is sold directly by cofounder Beat Weinmann from the ochs und junior workshop in Lucerne. You can select your perpetual calendar watch from models designed by ochs und junior in our online store. Or you can design your perpetual calendar using our online customizer. With pleasure, Weinmann will guide you to your perfect watch on the phone, over email, or in person.

Swiss made

The ochs und junior perpetual calendar is entirely manufactured in Switzerland. The case is manufactured by Peter Cantieni in Hinwil, while the gear system, dial, hands, buckle and crown are manufactured by Helfenstein in Alpnach. The Ulysse Nardin UN-118 base movement is manufactured in Le Locle. Each watch is hand-assembled and regulated at the ochs und junior workshop in Lucerne.

Lifetime warranty

A lifetime warranty covers all parts invented by Ludwig Oechslin, and the entire watch is covered by a 2-year guarantee. ochs und junior’s small scale and direct sales model allow it to offer uniquely fast and competent service.

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Jan  | Leap year

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Jan  | Leap year

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Jan  | Leap year

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Jan  | Leap year

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Jan  | Leap year

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Jan  | Leap year

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Feb  | Leap year

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Mar  | Leap year

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Apr  | Leap year

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May  | Leap year

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Jun  | Leap year

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Jul  | Leap year

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Dec  | Leap year

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Feb  | Leap year

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Feb  | Common year

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Feb  | Common year

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Feb  | Common year

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Full power reserve

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Feb  | Leap year
Empty power reserve

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Feb  | Leap year
Half power reserve

Reading the functions

The arrows next to the watch above allow you to show different dates. Reading Dr. Oechslin’s calendar becomes intuitive after a short time on the wrist.

Date

The 30+1 holes around the perimeter of the dial display the date. The 10 minute markers serve as reference points. For example: the marker indicating 30 minutes also shows the 15th day of the month (30÷2=15). These 5 day markers allow for the date to be read at a glance and after a short time, you can recognize the date intuitively.

Month

The 4 perforations in the month disk indicate the month. When the outermost perforation points to 1 o’clock, it is January. When the outermost perforation points to 2 o’clock, it is February. The month disk rotates clockwise.

Leap year

The 4 perforations in the month disk also show whether it is a leap year or a common year. When the outermost dot is orange, it is a leap year (366 days). When it is dark, it is a common year (365 days). The leap year disk rotates clockwise beneath the month disk.

Power reserve

The small circle beneath 12 o’clock is the power reserve indicator. Full power (60 hours) is when the dot is beneath the rightmost 12 o’clock marker. Empty is when the dot is beneath the leftmost 12 o’clock marker. The disk rotates counterclockwise.

Hour and minute

The exact minute can be read using the date holes, which are spaced at 2 minute intervals. Holes mark even minutes and gaps odd minutes.

Second

Just above the 6 o’clock marker is a seconds disk with a milled excentric dot. This disk shows the watch is running.

Control dot

The control dot is located between 1 and 2 o’clock. Together with the time, the control dot shows when it is okay to adjust the date. The video on the manual page shows how this works.

Mechanics

In the film above, Dr. Oechslin’s perpetual calendar function is assembled in Lucerne. The video is 23 minutes long and has no cuts. You can also watch a version of this video with Dr. Oechslin providing commentary.

How is Dr. Oechslin’s perpetual calendar function unique?

Dr. Oechslin executes his perpetual calendar as a gear system comprising 9 additional parts and 3 modified parts (*). You can observe these parts in the film. From right to left, they are:

  • Dial*
  • 12-hour ratchet wheel*
  • Date disk*
  • Baseplate for perpetual calendar mechanism
  • Date ratchet wheel
  • Bridge
  • Month ratchet wheel
  • Another bridge
  • In-between wheel
  • Month disk
  • 4 year ratchet wheel
  • Additional tooth

Each part is designed to solve multiple problems at once. Like in software engineering and architecture, a simpler solution is more difficult to achieve, but technical elegance brings significant benefits. If a solution requires fewer parts, there are fewer interactions between parts, and fewer potential sources of manufacturing error. Dr. Oechslin strives to develop the simplest possible solution because he wants a more reliable result – and he enjoys the intellectual challenge. His ability to reduce a perpetual calendar down to 9 additional parts is the only way ochs und junior, a company with 4 employees, could bring to market an original perpetual calendar function. Dr. Oechslin replaces the R&D and quality assurance departments with greater upfront thinking.

What was Dr. Oechslin’s motivation for using gears?

With their turning wheels, gears lend themselves to Dr. Oechslin’s goal of displaying the date, month and year in analog fashion, like the hands on a watch. The calendar information on Dr. Oechslin’s perpetual calendar is readable from the same distance as the time. Gears also allow Dr. Oechslin to invent solutions which use fewer parts. Fewer parts leads to higher reliability – and easier servicing. It’s why ochs und junior can offer a lifetime guarantee on the parts designed by Dr. Oechslin. Finally, his gear system enables all of the functions to be adjusted quickly via the crown; there is therefore no need for additional pushers like in conventional perpetual calendars. It is fun to set! Check out the “Forwards and backwards” video.

What is the base movement?

The Ulysse Nardin UN-118.

Who is Ludwig Oechslin?

The ochs und junior perpetual calendar is the result of Dr. Oechslin’s 40 year watchmaking career, during which he has continually returned to the challenge of displaying and implementing calendar watches. In the 1990s, Dr. Oechslin invented the first perpetual calendar watch with a date adjustable in both directions, the Ulysse Nardin Perpetual GMT.

Technical information

Dimensions

42mm x 12.5mm (incl. crystal)

Weight

76.4g in titanium (incl. leather strap and buckle)
119.1g in sterling silver 925 (incl. leather strap and buckle)

Water resistance

50m in titanium, 30m in sterling silver 925. Both models are fit for almost any situation in daily life. For swimming, we recommend titanium.

Case

2-part case designed by Ludwig Oechslin. Available in grade 5 titanium or sterling silver 925; additional materials upon request. Visible machining marks. ochs und junior watches require no movement ring due to the extremely small manufacturing tolerances on the case. Available exclusively with a solid case back. Manufacturer: Peter Cantieni / Hinwil / Switzerland.

Base movement

Ulysse Nardin UN-118 with 60 hours power reserve. Hand-regulated by ochs und junior to 0/+5 seconds per day. Manufacturer: Ulysse Nardin SA / Le Locle / Switzerland.

Crown

Screw-down crown designed by Ludwig Oechslin in grade 5 titanium or sterling silver 925. Manufacturers: Pibor SA / Glovelier / Switzerland and Helfenstein Mechanik AG / Alpnach / Switzerland.

Buckle

Designed by Ludwig Oechslin for 22mm watch straps with no loops. Visible machining marks. Grade 5 titanium or sterling silver 925, additional materials upon request. Manufacturer: Helfenstein Mechanik AG / Alpnach / Switzerland.

Watch straps

We offer over 80 possibilities, which you can explore in our straps pages: sturgeon, leather, suede, rubber.

Sapphire crystal

The sapphire crystals are manufactured by Stettler in Lyss / Switzerland. Both sides are treated with anti-reflective coating by Econorm in St-Imier / Switzerland.

Night visibility

To assure optimal readability of the time at night, we use Super-LumiNova X1. This coating is manufactured by RC TRITEC in Teufen / Switzerland. In principle, all Pantone colors can be made. Super-LumiNova is always applied in conjunction with a color pigment. The brighter the color, the better the luminosity. At night, Super-LumiNova shines green (the option used by ochs und junior) or blue, on special request. The Super-LumiNova coating is applied by hand by ochs und junior, or for dials with a color application by Cador in Eimeldingen / Germany and by Monyco in La Chaux-de-Fonds / Switzerland.

Designed by ochs und junior

Watches in the perpetual calendar store are designed by ochs und junior. Individually manufactured, they have the potential to become classics.

Custom-made

Ludwig Oechslin’s rigorously simple designs, the fact that we individually manufacture our parts, and the direct contact we have with our clients enable us to offer the highest possible degree of customization. The customizer shows many possibilities. We are also happy to discuss ideas which are not in the customizer with you. Please contact cofounder Beat Weinmann for a personal consultation.