| Millennium: | 1st millennium |
|---|---|
| Centuries: | |
| Decades: | |
| Years: |
| 721 by topic |
|---|
| Leaders |
| Categories |
| Gregorian calendar | 721 DCCXXI |
| Ab urbe condita | 1474 |
| Armenian calendar | 170 ԹՎ ՃՀ |
| Assyrian calendar | 5471 |
| Balinese saka calendar | 642–643 |
| Bengali calendar | 128 |
| Berber calendar | 1671 |
| Buddhist calendar | 1265 |
| Burmese calendar | 83 |
| Byzantine calendar | 6229–6230 |
| Chinese calendar | 庚申年 (Metal Monkey) 3418 or 3211 — to — 辛酉年 (Metal Rooster) 3419 or 3212 |
| Coptic calendar | 437–438 |
| Discordian calendar | 1887 |
| Ethiopian calendar | 713–714 |
| Hebrew calendar | 4481–4482 |
| Hindu calendars | |
| - Vikram Samvat | 777–778 |
| - Shaka Samvat | 642–643 |
| - Kali Yuga | 3821–3822 |
| Holocene calendar | 10721 |
| Iranian calendar | 99–100 |
| Islamic calendar | 102–103 |
| Japanese calendar | Yōrō 5 (養老５年) |
| Javanese calendar | 614–615 |
| Julian calendar | 721 DCCXXI |
| Korean calendar | 3054 |
| Minguo calendar | 1191 before ROC 民前1191年 |
| Nanakshahi calendar | −747 |
| Seleucid era | 1032/1033 AG |
| Thai solar calendar | 1263–1264 |
| Tibetan calendar | 阳金猴年 (male Iron-Monkey) 847 or 466 or −306 — to — 阴金鸡年 (female Iron-Rooster) 848 or 467 or −305 |
Year 721 (DCCXXI) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar. The denomination 721 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.