What if you adopted a 2014 calendar for this year 2025? This practice may seem surprising, but it is nevertheless completely correct, the days being identical between the two years. Mathematical logic even makes it possible to explain it.
It is an object that may seem outdated, but it is not. The paper calendar still has its fans. “It’s exactly like people who prefer to read printed books rather than on tablets, we are sensitive to paper,” explains the director of the Brachard stationery in 7:30 p.m., noting that sales remain stable, or even increasing.
But some go further, reusing calendars from the past. This is the case of four Genevans sharing a flat, always looking for second-hand objects: “We wondered if there were past years that had the same calendar as 2025,” explains one of them. them.
After some research on second-hand sites, they found a calendar from 2014, ready to use again. But they could also have reused a calendar from 2003, 1997 or even 1969.
Fourteen calendars for life
But how is this possible? The logic is simple: a common (non-leap) year can have its calendar reused after a cycle of six or eleven years. For leap years, the cycle differs slightly. In total, only fourteen calendar types are needed to cover all possible configurations.
“Then it remains to know in what order, which is a little more complicated,” admits mathematician David Cimasoni. Especially since the Gregorian calendar reserves some additional surprises, “like the particularities linked to the common years every hundred years”.
For those who plan to keep their 2025 calendar, know that it can be reused in 2031 and even up to the year… 2200.
Celine Argento
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