| Millennium: | 1st millennium |
|---|---|
| Centuries: | 8th century – 9th century – 10th century |
| Decades: | 770s 780s 790s – 800s – 810s 820s 830s |
| Years: | 801 802 803 – 804 – 805 806 807 |
| 804 by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishment and disestablishment categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 804 DCCCIV |
| Ab urbe condita | 1557 |
| Armenian calendar | 253 ԹՎ ՄԾԳ |
| Assyrian calendar | 5554 |
| Bahá'í calendar | -1040–-1039 |
| Bengali calendar | 211 |
| Berber calendar | 1754 |
| English Regnal year | N/A |
| Buddhist calendar | 1348 |
| Burmese calendar | 166 |
| Byzantine calendar | 6312–6313 |
| Chinese calendar | 癸未年十一月十五日 (3440/3500-11-15) — to —
甲申年十一月廿六日(3441/3501-11-26) |
| Coptic calendar | 520–521 |
| Ethiopian calendar | 796–797 |
| Hebrew calendar | 4564–4565 |
| Hindu calendars | |
| - Vikram Samvat | 860–861 |
| - Shaka Samvat | 726–727 |
| - Kali Yuga | 3905–3906 |
| Holocene calendar | 10804 |
| Iranian calendar | 182–183 |
| Islamic calendar | 188–189 |
| Japanese calendar | |
| Korean calendar | 3137 |
| Minguo calendar | 1108 before ROC 民前1108年 |
| Thai solar calendar | 1347 |
Year 804 (DCCCIV) was a leap year starting on Monday (link will display the full calendar) of the Julian calendar.