803
| Years | 
|---|
| Millennium | 
| 1st millennium | 
| Centuries | 
| Decades | 
| Years | 
| 803 by topic | 
|---|
| Leaders | 
| Categories | 
| 
 | 
| Gregorian calendar | 803 DCCCIII | 
| Ab urbe condita | 1556 | 
| Armenian calendar | 252 ԹՎ ՄԾԲ | 
| Assyrian calendar | 5553 | 
| Balinese saka calendar | 724–725 | 
| Bengali calendar | 209–210 | 
| Berber calendar | 1753 | 
| Buddhist calendar | 1347 | 
| Burmese calendar | 165 | 
| Byzantine calendar | 6311–6312 | 
| Chinese calendar | 壬午年 (Water Horse) 3500 or 3293 — to — 癸未年 (Water Goat) 3501 or 3294 | 
| Coptic calendar | 519–520 | 
| Discordian calendar | 1969 | 
| Ethiopian calendar | 795–796 | 
| Hebrew calendar | 4563–4564 | 
| Hindu calendars | |
| - Vikram Samvat | 859–860 | 
| - Shaka Samvat | 724–725 | 
| - Kali Yuga | 3903–3904 | 
| Holocene calendar | 10803 | 
| Iranian calendar | 181–182 | 
| Islamic calendar | 187–188 | 
| Japanese calendar | Enryaku 22 (延暦22年) | 
| Javanese calendar | 698–699 | 
| Julian calendar | 803 DCCCIII | 
| Korean calendar | 3136 | 
| Minguo calendar | 1109 before ROC 民前1109年 | 
| Nanakshahi calendar | −665 | 
| Seleucid era | 1114/1115 AG | 
| Thai solar calendar | 1345–1346 | 
| Tibetan calendar | 阳水马年 (male Water-Horse) 929 or 548 or −224 — to — 阴水羊年 (female Water-Goat) 930 or 549 or −223 | 
Year 803 (DCCCIII) was a common year starting on Sunday of the Julian calendar.