Year 648 (DCXLVIII) was a leap year starting on Tuesday (link will display the full calendar) of the Julian calendar. The denomination 648 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.
|Ab urbe condita||1401|
|Balinese saka calendar||569–570|
|Chinese calendar||丁未年 (Fire Goat)|
3344 or 3284
— to —
戊申年 (Earth Monkey)
3345 or 3285
|- Vikram Samvat||704–705|
|- Shaka Samvat||569–570|
|- Kali Yuga||3748–3749|
|Japanese calendar||Taika 4|
|Minguo calendar||1264 before ROC|
|Seleucid era||959/960 AG|
|Thai solar calendar||1190–1191|
774 or 393 or −379
— to —
775 or 394 or −378
- Emperor Constans II issues an imperial edict forbidding Monothelitism to be discussed, to quiet the intense controversy caused by the Monothelete doctrine. This edict, distributed by patriarch Paul II in Constans' name, is known as the Typos.
- King Sigebert II of Austrasia is advised by Remaclus to establish a double-monastery, at Stavelot and Malmedy. As a missionary bishop, he founds an abbey on the River Amblève (modern Belgium).
- King Cenwalh of Wessex returns from a 3-year exile in East Anglia, to reclaim his kingdom. He gives 3,000 hides of land around Ashdown to his nephew Cuthred, possibly sub-king of Berkshire (England).
- Cenwahl invites bishop Birinus to establish under his direction the Old Minster in Winchester. Together they have a small stone church built.
- Tang general Ashina She'er re-establishes Tang control of Karasahr, and leads a military campaign against the Tarim Basin kingdom of Kucha in Xinjiang, a vassal of the Western Turkic Khaganate.
- In an early skirmish in the run up to the Second Tikal-Calakmul War, B'alaj Chan K'awiil scores a military victory, apparently over his half-brother, who had galled him by using the same royal emblem (or emblem glyph) as he did.
- Dos Pilas breaks away from Tikal and becomes a vassal state of Calakmul.
- The Book of Jin is compiled in China during the Tang Dynasty. Its chief editor is the chancellor Fang Xuanling, who dies in this year as well.