1815 Rattrapante Perpetual Calendar is a luxury wristwatch by A. Lange & Söhne.

This model was introduced 2013. It combines two sophisticated, classic complications in one wristwatch: a chronograph with rattrapante function and a perpetual calendar with moon phase indication.

The dial is made of solid silver, and solid red gold for the white gold model released in 2023. The hands are made of rhodium-plated gold, blued steel, and gold-plated steel.

While the rattrapante chronograph masters the measurement of various time intervals down to the fraction of a second, the technical mastery of the perpetual calendar lies in its “long-term memory”. The complex and proverbial forward-looking mechanism ensures the exact representation of the date, day of the week and month every day for decades, even taking leap years into account. Only on March 1 2100 does the calendar display have to be corrected by one day, because then, according to the regulations of the Gregorian calendar, the leap year no longer applies.

The moon phase display is also programmed for the long term. It shows the synodic orbital period of the earth's satellite so exactly that it has to be corrected by one day only in 122.6 years.