|Ab urbe condita||1998|
|Balinese saka calendar||1166–1167|
|English Regnal year||29 Hen. 3 – 30 Hen. 3|
|Chinese calendar||甲辰年 (Wood Dragon)|
3941 or 3881
— to —
乙巳年 (Wood Snake)
3942 or 3882
|- Vikram Samvat||1301–1302|
|- Shaka Samvat||1166–1167|
|- Kali Yuga||4345–4346|
|Japanese calendar||Kangen 3|
|Minguo calendar||667 before ROC|
|Thai solar calendar||1787–1788|
1371 or 990 or 218
— to —
1372 or 991 or 219
|Wikimedia Commons has media related to 1245.|
- February 21 – Thomas (bishop of Finland) is granted resignation by Pope Innocent IV, after having confessed to torture and forgery.
- April 16 – Pope Innocent IV sends Giovanni da Pian del Carpine to the Mongol court, suggesting (amongst other things) that the Mongols convert to Christianity, and join the Crusades.
- June 28 – The First Council of Lyon opens, in the course of which Frederick II, Holy Roman Emperor, is excommunicated and deposed, and the Seventh Crusade is proclaimed.
- August 1 – The second of two papal bulls refers to the marriage of King Sancho II of Portugal to Mécia Lopes de Haro, and decrees the deposition of the king.
- date unknown
- January 16 – Edmund Crouchback, 1st Earl of Lancaster, son of Henry III of England (d. 1296)
- April 3 – King Philip III of France (d. 1285)
- November 14 — Sang Sapurba, first Malay King and progenitor of Malay kings in Malacca and Majapahit kingdoms (d. 1316)
- date unknown – Boniface of Savoy