29.02.2024 - Patek Philippe

Annual vs Perpetual Calendar Watches

A calendar complication is common in many watches. However, some can require regular adjustment to ensure that the correct date is displayed. This is due to the number of days in months varies throughout the year. Complete calendar watches require adjustment any time the number of days in a month varies (5 times per year), so watchmakers developed a solution to combat this. This solution came in the form of annual calendar and perpetual calendar complications.

The following blog looks at what these are, how they work and most importantly, what the key differences between them are.

Contents:

What Is An Annual Calendar Watch?
How Does An Annual Calendar Work?
What Is A Perpetual Calendar Watch?
How Does A Perpetual Calendar Work?
What’s the Difference Between Annual and Perpetual Calendar Watches?
The Best Annual Calendar Watches
The Best Perpetual Calendar Watches
FAQs

What Is An Annual Calendar Watch?

An annual calendar watch includes a complication that displays the day, date and month on the watch face. They require minimal adjustment, automatically updating based on 30 and 31 day months. However, to ensure that the correct date is always displayed, they must be adjusted once per year at the end of February. This is because February is a shorter month, and contains a leap year every 4 years, which the complication is unable to account for. For the other 11 months in the year, the movement will automatically adjust between 30 or 31 days. 

Whilst wristwatch calendars have been around since the 1920’s, the annual calendar wasn’t introduced and patented until 1996 by Patek Philippe. The annual calendar watch was designed to be easy to use, requiring less corrections than the standard Complete Calendar watches that need adjustment 5 times per year. 

Their introduction also appealed to a new generation of watch enthusiasts, as they tend to retail at a lower price point than perpetual calendar watches. This is because perpetual watches are renowned for their delicate and complex inner workings, whilst the annual calendar watch complication is more simplistic in nature. This can also mean mechanical reliability is improved.

How Does An Annual Calendar Work?

The annual calendar complication sits on wheels that rotate each day and are displayed through an aperture on the watch face. The month wheel has 12 teeth to account for each month, with 5 longer teeth representing the 30 day months. These longer teeth cause the mechanism to rotate an additional time when engaged, skipping past the 31st date when it is not needed. The weekday wheel will rotate by one tooth per day continuously to display the correct day.

What Is A Perpetual Calendar Watch?

Perpetual calendar watches contain a complication that advances the day, date and month automatically without adjustment. They take into account 30 and 31 day months, as well as the shorter February month and leap years. This is because perpetual calendar watches know the year, meaning without mechanical failure, they will run accurately until the year 2100 when the leap year will be skipped.

Many perpetual calendar watches also show the moonphase and include a leap year indicator, displaying this on the watch face alongside the day, date and month.

This complication precedes the Annual Calendar, first appearing in 1762 in a pocket watch. Until 1864 however, it was largely unused, until Patek Philippe released a perpetual calendar pocket watch. It was not until 1889 that Patek Philippe patented the complication, eventually releasing a perpetual calendar wrist watch in 1898.

This large gap in the production of perpetual calendar watches is likely due to their highly complex and delicate nature. Because of this, up until the 1940’s, most perpetual calendar watches were commission-only. This complexity also means they tend to retail at a higher price point than annual calendar watches.

How Does A Perpetual Calendar Work?

The movements powering a perpetual calendar are intricate and complex, often requiring hundreds of mechanical parts to be used. The movement uses the wheels, gears, and levers to calculate the 1,461 days (four years) to display the correct date. 

One of the wheels will rotate fully once every 4 years, repeating to account for the leap year. Whilst each watch can be slightly different, most perpetual calendar watches will have a separate mechanism for each the day, date and month. A long lever, known as the ‘grand lever’ synchronises each of the mechanisms. The lever will move backwards and forwards depending on the month length, causing different wheels to move to display the correct date.

What’s the Difference Between Annual and Perpetual Calendar Watches?

The main difference between an annual and perpetual calendar watch is the amount of adjustment needed. Whilst annual calendar complications take into account 30 and 31 days months, they cannot account for the shorter February month or leap years. Perpetual calendar watches on the other hand are designed to work ‘perpetually’, until the year 2100, using a 4 year mechanism cycle. 

There are some other key differences between perpetual and annual calendar watches summarised in the table below:

Annual CalendarPerpetual Calendar
AdjustmentsOnce per year at the end of FebruaryNo adjustment needed until 2100
ComplexityMore simplistic mechanism made up of ~5 partsComplex mechanism made up of hundreds of parts
PriceTend to retail at a lower price pointTend to retail at a higher price point
Patented19961889

The Best Annual Calendar Watches

Patek Philippe 5396G

The Patek Philippe 5396G is an annual calendar watch that will satisfy even the most passionate and discerning luxury watch connoisseur. Featuring a stainless steel case, the 5396G-011 has a design that never goes out of style. With a sleek black dial, standout hour markers and a sapphire-crystal case back, the Patek Philippe 5396G-011 is aesthetically flawless.

Patek Philippe 5235/50R-001

The Patek Philippe 5235/50R-001 revisits the unique style of its Annual Calendar Regulator by presenting it in a rose gold case. With a two-tone graphite and ebony black dial, with a vertical satin finish and white transfer print and sapphire-crystal case back, the Patek Philippe 5235/50R-001 is as sophisticated as it is practical.

Patek Philippe 4947G-001

The Patek Philippe 4947G-001 ladies watch has a patented annual calendar that only needs to be corrected once a year. Featuring a white gold case, the Patek Philippe 4947G-001 has a bold feminine design. With a metallic blue dial, gold applied numerals and sapphire crystal case back, the Patek Philippe 4947G-001 has a cool and elegant design.

The Best Perpetual Calendar Watches

Patek Philippe 5270/1R-001

The Patek Philippe 5270/1R-001 Grand Complications has a manually wound mechanical movement and a CH 29-535 PS Q Caliber. This Grand Complications has an ebony black sunburst dial, displaying the day and the month in a double aperture at 12 o’clock and an analogue date at 6 o’clock. In addition to oozing a luxury feel, the Patek Philippe 5270/1R-001 also has sandblasted hands, which combines sleek style with modern legibility. The Patek Philippe 5270/1R-001 has a rose gold “Gouette” bracelet that perfectly blends with the case for a seamless finish.

Patek Philippe 5496P-015

The Patek Philippe 5496P-015 Grand Complications has a self winding mechanical movement and a 324 S QR Caliber. This Grand Complications has a platinum case and sapphire crystal case back protected by a hinged dust cover. This particular model also takes advantage of Patek Philippe’s mechanical memory function which allows the calendar to show day, date, month and leap year days. The Patek Philippe 5496P-015 has an Opaline-white dial, hand guilloched centre and rose gold polished hour markers and hands that is a watch collector’s dream. 

Patek Philippe 5320G-001

The Patek Philippe 5320G-001 Grand Complications has self winding mechanical movement and perpetual calendar and day, date, month, leap year and 24-hour indicators. The Patek Philippe 5320G-001 has an 18k white gold case with an Interchangeable full back and sapphire-crystal case back and sweep seconds hand. This Grand Complications case has three-tier lugs as well as a lacquered cream dial including luminous numerals and hands. The Patek Philippe 5320G-001 has a newly developed calibre 324 with double apertures for the day/month and an analogue date and is highly desired by watch collectors and enthusiasts alike.

If you own a Patek Philippe timepiece with an annual or perpetual calendar and are looking to sell or get a quote, then we are here to help. With our Get A Quote form it’s never been easier to have your watch valued. Sell your Patek Philippe watch to us and receive the best possible price.

FAQs

How many years is a perpetual calendar?

Perpetual calendars are designed to be just that – perpetual. However, perpetual calendar complications will only run accurately until the year 2100 when the leap year will be skipped, meaning the watch date will no longer be correct.

What happens to a perpetual calendar after 2100?

In 2100, the leap year will be skipped causing perpetual calendar watch dates to be incorrect. The watch will need to be adjusted by 1 day on March 1st 2100. 

Why will perpetual calendar watches need to be adjusted in 2100?

Perpetual calendar watches are based on the Gregorian calendar. We add a leap year every 4 years as the Sidereal year (the time in which the earth completes one revolution in its orbit around the sun) is actually shorter than the calendar year. By adding an additional day, we actually make the calendar year longer by about 44 minutes each year which over time cumulates. To counteract this, and stop the seasons from changing, we skip the leap year if the year is divisible by 100 and not divisible by 400. This rule means the next leap year that will be skipped is 2100.

What is the benefit of an annual calendar watch vs a perpetual calendar watch?

Annual calendar watches tend to retail at a lower price point than perpetual calendar watches so can be open to a wider range of budgets. Their mechanisms are also more simplistic than perpetual calendar watches so mechanical failures may be less likely. However, on the whole perpetual calendar watches are reliable due to their high levels of craftsmanship.

What is the benefit of a perpetual calendar watch vs an annual calendar watch?

Perpetual calendar watches require the least adjustment of any complication type. Whilst annual calendar watches need adjusting once per year, and complete calendar watches 5 times per year, the perpetual calendar watch will not need adjusting until 2100. 

Can perpetual calendar watches be adjusted?

Perpetual calendar watches should not need regular adjustment, however should the watch stop they can be adjusted via the winding crown. Should a larger scale adjustment be needed, you may want to take the watch to a professional to ensure if it aligns to the correct year, ensuring the day/date/time remains accurate.