| Millennium: | 1st millennium |
|---|---|
| Centuries: | |
| Decades: | |
| Years: |
| 645 by topic |
|---|
| Leaders |
| Categories |
| Gregorian calendar | 645 DCXLV |
| Ab urbe condita | 1398 |
| Armenian calendar | 94 ԹՎ ՂԴ |
| Assyrian calendar | 5395 |
| Balinese saka calendar | 566–567 |
| Bengali calendar | 52 |
| Berber calendar | 1595 |
| Buddhist calendar | 1189 |
| Burmese calendar | 7 |
| Byzantine calendar | 6153–6154 |
| Chinese calendar | 甲辰年 (Wood Dragon) 3342 or 3135 — to — 乙巳年 (Wood Snake) 3343 or 3136 |
| Coptic calendar | 361–362 |
| Discordian calendar | 1811 |
| Ethiopian calendar | 637–638 |
| Hebrew calendar | 4405–4406 |
| Hindu calendars | |
| - Vikram Samvat | 701–702 |
| - Shaka Samvat | 566–567 |
| - Kali Yuga | 3745–3746 |
| Holocene calendar | 10645 |
| Iranian calendar | 23–24 |
| Islamic calendar | 24–25 |
| Japanese calendar | Taika 1 (大化元年) |
| Javanese calendar | 536–537 |
| Julian calendar | 645 DCXLV |
| Korean calendar | 2978 |
| Minguo calendar | 1267 before ROC 民前1267年 |
| Nanakshahi calendar | −823 |
| Seleucid era | 956/957 AG |
| Thai solar calendar | 1187–1188 |
| Tibetan calendar | 阳木龙年 (male Wood-Dragon) 771 or 390 or −382 — to — 阴木蛇年 (female Wood-Snake) 772 or 391 or −381 |
Year 645 (DCXLV) was a common year starting on Saturday (link will display the full calendar) of the Julian calendar. The denomination 645 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.