Leap year
After midnight on February 29th, the date automatically adjusts to March 1st.

Common year
After midnight on February 28th, the date automatically adjusts to March 1st.

Months with 30 days
After midnight on the 30th, the date automatically adjusts to the 1st of the next month.

Forwards and backwards
The date can be rapidly adjusted both forwards and backwards.

Ludwig Oechslin
Commentary on the assembly of his perpetual calendar

Ludwig Oechslin
Using gears

Ludwig Oechslin
Date displays

Ludwig Oechslin
Month display

Ludwig Oechslin
Functionality

Ludwig Oechslin
Prototyping

Ludwig Oechslin
Thinking more upfront

Ludwig Oechslin
Design

Ludwig Oechslin
Design trends

Ludwig Oechslin
Communication

Ludwig Oechslin
Mathematics

Ludwig Oechslin
Reliability

Ludwig Oechslin
Rigorous simplicity

Ludwig Oechslin
Teamwork

Ludwig Oechslin
The concept of ochs und junior

Ludwig Oechslin
Good luck

Ludwig Oechslin
Goals