31 BC

Millennium: 1st millennium BC
Centuries:
Decades:
Years:
31 BC in various calendars
Gregorian calendar31 BC
XXXI BC
Ab urbe condita723
Ancient Egypt eraXXXIII dynasty, 293
- PharaohCleopatra VII, 21
Ancient Greek era187th Olympiad, year 2
Assyrian calendar4720
Balinese saka calendarN/A
Bengali calendar−623
Berber calendar920
Buddhist calendar514
Burmese calendar−668
Byzantine calendar5478–5479
Chinese calendar己丑年 (Earth Ox)
2667 or 2460
    — to —
庚寅年 (Metal Tiger)
2668 or 2461
Coptic calendar−314 – −313
Discordian calendar1136
Ethiopian calendar−38 – −37
Hebrew calendar3730–3731
Hindu calendars
 - Vikram Samvat26–27
 - Shaka SamvatN/A
 - Kali Yuga3070–3071
Holocene calendar9970
Iranian calendar652 BP – 651 BP
Islamic calendar672 BH – 671 BH
Javanese calendarN/A
Julian calendar31 BC
XXXI BC
Korean calendar2303
Minguo calendar1942 before ROC
民前1942年
Nanakshahi calendar−1498
Seleucid era281/282 AG
Thai solar calendar512–513
Tibetan calendar阴土牛年
(female Earth-Ox)
96 or −285 or −1057
    — to —
阳金虎年
(male Iron-Tiger)
97 or −284 or −1056
The Battle of Actium

Year 31 BC was either a common year starting on Tuesday, Wednesday or Thursday or a leap year starting on Tuesday or Wednesday (link will display the full calendar) of the Julian calendar (the sources differ, see leap year error for further information) and a common year starting on Tuesday of the Proleptic Julian calendar. At the time, it was known as the Year of the Consulship of Antonius and Caesar or as Caesar and Messalla (or, less frequently, year 723 Ab urbe condita). The denomination 31 BC for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.