| Millennium: | 1st millennium |
|---|---|
| Centuries: | |
| Decades: | |
| Years: |
| 638 by topic |
|---|
| Leaders |
| Categories |
| Gregorian calendar | 638 DCXXXVIII |
| Ab urbe condita | 1391 |
| Armenian calendar | 87 ԹՎ ՁԷ |
| Assyrian calendar | 5388 |
| Balinese saka calendar | 559–560 |
| Bengali calendar | 45 |
| Berber calendar | 1588 |
| Buddhist calendar | 1182 |
| Burmese calendar | 0 |
| Byzantine calendar | 6146–6147 |
| Chinese calendar | 丁酉年 (Fire Rooster) 3335 or 3128 — to — 戊戌年 (Earth Dog) 3336 or 3129 |
| Coptic calendar | 354–355 |
| Discordian calendar | 1804 |
| Ethiopian calendar | 630–631 |
| Hebrew calendar | 4398–4399 |
| Hindu calendars | |
| - Vikram Samvat | 694–695 |
| - Shaka Samvat | 559–560 |
| - Kali Yuga | 3738–3739 |
| Holocene calendar | 10638 |
| Iranian calendar | 16–17 |
| Islamic calendar | 16–17 |
| Japanese calendar | N/A |
| Javanese calendar | 528–529 |
| Julian calendar | 638 DCXXXVIII |
| Korean calendar | 2971 |
| Minguo calendar | 1274 before ROC 民前1274年 |
| Nanakshahi calendar | −830 |
| Seleucid era | 949/950 AG |
| Thai solar calendar | 1180–1181 |
| Tibetan calendar | 阴火鸡年 (female Fire-Rooster) 764 or 383 or −389 — to — 阳土狗年 (male Earth-Dog) 765 or 384 or −388 |
Year 638 (DCXXXVIII) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar. The denomination 638 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.