323 (CCCXXIII) was a common year starting on Tuesday of the Julian calendar, the 323rd year of the Common Era (CE) and Anno Domini (AD) designations, the 323rd year of the 1st millennium, the 23rd year of the 4th century, and the 4th year of the 320s decade. As of the start of 323, the Gregorian calendar was 1 day ahead of the Julian calendar, which was the dominant calendar of the time.

Millennium: 1st millennium
Centuries: 3rd century4th century5th century
Decades: 290s  300s  310s  – 320s –  330s  340s  350s
Years: 320 321 322323324 325 326
323 in other calendars
Gregorian calendar323
CCCXXIII
Ab urbe condita1076
Assyrian calendar5073
Balinese saka calendar244–245
Bengali calendar−270
Berber calendar1273
Buddhist calendar867
Burmese calendar−315
Byzantine calendar5831–5832
Chinese calendar壬午(Water Horse)
3019 or 2959
    — to —
癸未年 (Water Goat)
3020 or 2960
Coptic calendar39–40
Discordian calendar1489
Ethiopian calendar315–316
Hebrew calendar4083–4084
Hindu calendars
 - Vikram Samvat379–380
 - Shaka Samvat244–245
 - Kali Yuga3423–3424
Holocene calendar10323
Iranian calendar299 BP – 298 BP
Islamic calendar308 BH – 307 BH
Javanese calendar204–205
Julian calendar323
CCCXXIII
Korean calendar2656
Minguo calendar1589 before ROC
民前1589年
Nanakshahi calendar−1145
Seleucid era634/635 AG
Thai solar calendar865–866
Tibetan calendar阳水马年
(male Water-Horse)
449 or 68 or −704
    — to —
阴水羊年
(female Water-Goat)
450 or 69 or −703

Events change