How to Buy a Calendar Watch (and What You Need to Know About Them)

Choose one of these mechanical marvels that will track the date on your wrist the old-fashioned analog way.

Tracking leap years is critical for calendar watches, and it wasn’t until 1955 that the 1-4 indicator, seen here on the Patek Philippe 5940G, made its way to the dial. Cramming all 31 days of the month would render the dial illegible, so only the odd numbers are shown. Even with the reduction, it gets a little tight between the 31 and 1. This not-quite-round, not-quite-square case is unique to Patek Philippe. The extra-wide space on the dial gives the additional numbers on the face room to breathe.

Tracking leap years is critical for calendar watches, and it wasn’t until 1955 that the 1-4 indicator, seen here on the Patek Philippe 5940G, made its way to the dial. Cramming all 31 days of the month would render the dial illegible, so only the odd numbers are shown. Even with the reduction, it gets a little tight between the 31 and 1. This not-quite-round, not-quite-square case is unique to Patek Philippe. The extra-wide space on the dial gives the additional numbers on the face room to breathe.

Photographer: Victor Prado for Bloomberg Pursuits

Like most wristwatches, the calendar watch is a descendant of the sundial, which various ancient cultures carefully calibrated to a specific spot on the earth so the sun’s shadow would fall in exactly the right position over the face. But a watch that would tell the date, month, and year has only recently made its way from oversize pocket types to something more wearable.

“A calendar watch is not only a mechanical computer,” says John Reardon, international head of watches for Christie’s, “but also an artistic representation of the passing of time. Layers of mechanical artistry must work in perfect harmony to present a seemingly simple result: what day it is.”

The Patek Philippe 5940G (seen above) is a perpetual calendar watch. It automatically accounts for the shorter months, and even adjusts for the notorious challenge of February—that this month adds a day once every four years has bedeviled watchmakers for generations. The timepiece is also one of the slimmest self-winding ones on the market, and the latest in the brand’s collection since it kick-started the trend in 1925, says David Bonilla, technical manager of Patek Philippe in New York. And as long as you keep it wound, you won’t need to adjust it until March  1, 2100, the next time our calendar skips a leap year. It might even be your great-grandson who will do it. Patek Philippe 5940G, $87,300; patek.com

 

FAQ: The Perpetual Calendar

Claudio Cavaliere, global brand ambassador for Audemars Piguet, on his everyday favorite

Why do you wear a perpetual calendar watch as your daily timepiece?
It’s a synthesis of time, space, and engineering and therefore speaks naturally to a large majority of watch lovers.

As a designer, what is the biggest challenge in making one?
We need to add more than 160 components in about 1.8  millimeters of space. Some of those are as thin as a single hair, and they all need to be adjusted perfectly. In addition, the movement is extra-thin, which adds complexity because the space to make adjustments is very limited. 

What’s your favorite historic calendar watch?
In 1955, Audemars Piguet introduced the first perpetual calendar wristwatch with the indication of the leap year. Only nine examples were made between 1955 and 1957. Although the ref. 5516 is 60  years old, it still looks so contemporary.

Other than those from Audemars Piguet, what’s the top calendar watch today?
The Greubel Forsey Quantième Perpétuel à Équation. It uses clever technical solutions.

 

4 Types to Buy

Illustration by Kristian Hammerstad for Bloomberg Pursuits

Date Calendar

Consider it a gentle introduction to the idea of a calendar watch. The gold standard of this category is the Rolex Day-Date 40, which displays the date on the right-hand side at 3 o’clock and the day of the week written across the top in a straightforward, less-is-more way—a design that’s remained mostly unchanged since it made its debut in 1956.

Rolex Day-Date 40, $37,550

 

 

 

Illustration by Kristian Hammerstad for Bloomberg Pursuits

Full Calendar

Now we’re talking. The day, date, and month are the three critical components of this watch, but it usually also includes an indicator for the phases of the moon, adding a little romance. Appropriately enough, the dial of this special edition Jaeger-LeCoultre Master Calendar is made from a sliver of real meteorite. 

Jaeger-LeCoultre Master Calendar, $12,600

 

 

 

Illustration by Kristian Hammerstad for Bloomberg Pursuits

Annual Calendar

All the information of the full calendar, with more convenience: You need to push the watch forward only at the end of February. The Rotonde de Cartier ingeniously positions the days of the week around the edge, while the month is located in a curved window at 6 o’clock. A large numerical date is right up top at 12 o’clock. 

Rotonde de Cartier Annual Calendar, $38,200

 

 

 

Illustration by Kristian Hammerstad for Bloomberg Pursuits

Perpetual Calendar

You’ve arrived. These finely tuned machines account for leap years as well as the day, date, and month, so you need to adjust it only when a leap year is skipped (roughly every 100  years). Although there’s no day of the week indicator on the H Moser Endeavour, a small arrow points out from the hour and minute hands to the 12-hour markers to indicate the month. 

H Moser Endeavour Perpetual  Calendar, $52,000

 

 

 

A Social Network for Watch Obsessives 

If you prefer a Facebook feed filled with pictures of a 1964 Rolex or the newest Linde Werdelin, then sign up for 8 Past 10, a social network started by Kristian Haagen, author of the new book Hashtags & Watches. Named for the time that watches are usually set to in stores, the site (an app is coming soon) lets you share photos, rate contributions, and keep up with watchworthy news.

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