About

The Pataphysical Calendar is a 13-month system devised by the Collège de 'Pataphysique, rooted in Alfred Jarry's science of imaginary solutions. Each month contains exactly 29 days, yielding 377 nominal days overlaid onto the Gregorian 365 or 366. The epoch is 8 September 1873 (Gregorian), corresponding to 1 Absolu of year 1 of the Pataphysical Era (E.P.). Months bear names such as Absolu, Haha, As, Sable, Décervelage, Gueules, Pédale, Clinamen, Palotin, Merdre, Gidouille, Tatane, and Phalle. Every day is assigned a patron saint drawn from the Pataphysical hagiography. Conversion errors propagate silently: miscounting the imaginary 29th of Gidouille (the Hunyadi intercalary day, which exists only in leap years) shifts every subsequent date by one. This tool implements the complete mapping, including intercalary logic, saint lookups, and feast importance classification.

Formulas

The Pataphysical year Y_p for a given Gregorian date is determined by the offset from the epoch.

Y_p = Y_g − 1873 + 1

This holds when the Gregorian date falls on or after 8 September. If before 8 September, Y_p = Y_g − 1873. The month M_p and day D_p are found by computing the day-of-year offset from 8 September, then dividing into 29-day blocks:

M_p = floor(offset ÷ 29) + 1

D_p = (offset mod 29) + 1

Where offset is the number of days from 8 September of the current Pataphysical year (wrapping at year boundary). The intercalary Hunyadi day (29 Gidouille) is inserted only when the next Gregorian year is a leap year. On that day, the calendar pauses - it is an imaginary day outside normal counting. Where Y_g = Gregorian year, Y_p = Pataphysical year (E.P.).

Reference Data

Month #	Pataphysical Month	Gregorian Start	Days	Notable Saint (Day 1)
1	Absolu	8 Sept	29	Nativité d'Alfred Jarry
2	Haha	7 Oct	29	St Ablou
3	As	5 Nov	29	St Aaou
4	Sable	4 Dec	29	St Oukase
5	Décervelage	2 Jan	29	Ste Bouse
6	Gueules	31 Jan	29	St Mouche
7	Pédale	1 Mar	29	St Tic
8	Clinamen	30 Mar	29	St Glu
9	Palotin	28 Apr	29	Ste Crotte
10	Merdre	27 May	29	St Viole
11	Gidouille	25 Jun	28/29	St Marais
12	Tatane	24 Jul	29	Ste Mélusine
13	Phalle	22 Aug	29	Ste Stupeur

Frequently Asked Questions

February 29 (Gregorian leap day) corresponds to 29 Gidouille in the Pataphysical Calendar. This is the Hunyadi intercalary day - an imaginary day that exists only in leap years. The Collège de 'Pataphysique considers it a day outside the normal continuum, dedicated to the memory of St Hunyadi.

September 8, 1873 is the birth date of Alfred Jarry, the creator of Pataphysics. The Collège de 'Pataphysique designated this as the epoch (1 Absolu 1 E.P.). Every Pataphysical new year begins on September 8 of the Gregorian calendar.

13 × 29 = 377 nominal days, but the calendar overlays the Gregorian year directly. Each Pataphysical month starts on a fixed Gregorian date (e.g., Absolu on Sept 8, Haha on Oct 7). Days beyond the Gregorian year length are simply absent - specifically, 29 Gidouille only exists in leap years, and certain month boundaries absorb the difference. In practice, the mapping produces 365 real days (366 in leap years).

Each day in the Pataphysical Calendar has a patron saint from the Pataphysical hagiography. These saints are drawn from literature, absurdist philosophy, and the Ubu cycle. Feast days are classified by importance: fête suprême (first, second, third, or fourth class), with supreme first-class feasts being the most significant celebrations in the Pataphysical liturgical cycle.

Technically, the Pataphysical Calendar extends backward (producing negative or pre-epoch years), but the Collège de 'Pataphysique has not formally defined saint days or feast importances for dates before the epoch. This converter supports pre-epoch dates by computing the year as negative E.P., but saint lookups will still cycle through the standard hagiographic table.

No. The Pataphysical Calendar is defined exclusively as an overlay on the proleptic Gregorian calendar. It does not reference the Julian calendar. If you input a date before October 15, 1582, the converter treats it as a proleptic Gregorian date, which may differ from the historical Julian date by several days.