The Pisan calendar, also referred to as the ''stile pisano'' ("Pisan style") or the ''calculus Pisanus'' ("Pisan calculation"), was the

calendar A calendar is a system of organizing days. This is done by giving names to periods of time, typically days, weeks, months and years. A calendar date, date is the designation of a single and specific day within such a system. A calendar is ...

used in the Republic of Pisa in Italy during the Middle Ages, which differed from the traditional

Julian calendar The Julian calendar is a solar calendar of 365 days in every year with an additional leap day every fourth year (without exception). The Julian calendar is still used as a religious calendar in parts of the Eastern Orthodox Church and in parts ...

Beginning of the year

The Pisan year began on 25 March, and not on 1 January, with the apparent year lying ahead of the traditional Julian calendar.. Thus, 24 March 1200 was followed by 25 March 1201 (not 1200, as it would remain in the Julian calendar), and 31 December 1201 would then be followed by 1 January 1201, which was the point at which the two calendars synchronised. This is the reason that most dates have an apparent discrepancy of one year, as the two calendars differ for just over nine months of each cycle. For example, a birth date of 10 September 1552 in Pisan reckoning translates to 10 September 1551 in the Julian calendar. Beginning the year on a date other than 1 January was common during the mediaeval period. The first day of the year falling on 25 March meant that the Pisan calendar was in the ''stile dell'Annunciazione'' ("style of the Annunciation") or ''stile dell'Incarnazione'' ("style of the Incarnation") - also styled in Latin as ''ab ominicaincarnatione'' ("by the ord'sIncarnation") - by reference to the Solemnity of the Annunciation, and similar calendars saw use in

Cortona Cortona (, ) is a town and ''comune'' in the province of Arezzo, in Tuscany, Italy. It is the main cultural and artistic centre of the Val di Chiana after Arezzo. Toponymy Cortona is derived from Latin Cortōna, and from Etruscan language, Etr ...

and Pistoia. The Florentine, Sienese, English and Scottish calendars were also in this style, but confusingly ran behind the Julian calendar rather than ahead, resulting in them lying exactly one year behind of the Pisan calendar. By contrast, calendars in the ''stile della Natività'' ("style of the Nativity") as in

Arezzo Arezzo ( , ; ) is a city and ''comune'' in Italy and the capital of the Province of Arezzo, province of the same name located in Tuscany. Arezzo is about southeast of Florence at an elevation of Above mean sea level, above sea level. As of 2 ...

Assisi Assisi (, also ; ; from ; Central Italian: ''Ascesi'') is a town and comune of Italy in the Province of Perugia in the Umbria region, on the western flank of Monte Subasio. It is generally regarded as the birthplace of the Latin poet Prope ...

and

Perugia Perugia ( , ; ; ) is the capital city of Umbria in central Italy, crossed by the River Tiber. The city is located about north of Rome and southeast of Florence. It covers a high hilltop and part of the valleys around the area. It has 162,467 ...

began on the Solemnity of the Nativity of the Lord (Christmas) on 25 December, the Venetian calendar began on 1 March until the Fall of the Venetian Republic, and the French year on

Easter Easter, also called Pascha ( Aramaic: פַּסְחָא , ''paskha''; Greek: πάσχα, ''páskha'') or Resurrection Sunday, is a Christian festival and cultural holiday commemorating the resurrection of Jesus from the dead, described in t ...

day until 1564. The traditional Julian calendar was sometimes said to be in the ''stile della Circoncisione'' ("style of the Circumcision"). See beginning of the year.

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Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

was one of the few regions to immediately convert from the Julian calendar to the Gregorian: 4 October 1582 was followed by 15 October 1582, the latter being the first day of the new Gregorian calendar. Not until 1749, however, were the ancient calendars definitively outlawed in

Tuscany Tuscany ( ; ) is a Regions of Italy, region in central Italy with an area of about and a population of 3,660,834 inhabitants as of 2025. The capital city is Florence. Tuscany is known for its landscapes, history, artistic legacy, and its in ...

: in that year the recently appointed Grand Duke and

Holy Roman Emperor The Holy Roman Emperor, originally and officially the Emperor of the Romans (disambiguation), Emperor of the Romans (; ) during the Middle Ages, and also known as the Roman-German Emperor since the early modern period (; ), was the ruler and h ...

, Francis I, ordered that, starting from 1750, the first of January should become the first day of the year, thus having the "peoples of Tuscia" conform to all the others. A plaque in Latin commemorating the grand ducal/imperial decree is affixed to the west wall of the Loggia dei Lanzi, in

Piazza della Signoria () is a w-shaped Town Square, square in front of the in Florence, Central Italy. It was named after the Palazzo della Signoria, also called . It is the main point of the origin and history of the Florentine Republic and still maintains its reput ...

Florence Florence ( ; ) is the capital city of the Italy, Italian region of Tuscany. It is also the most populated city in Tuscany, with 362,353 inhabitants, and 989,460 in Metropolitan City of Florence, its metropolitan province as of 2025. Florence ...

Beginning of the year

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Notes

References

Further reading