|828 by topic|
|Ab urbe condita||1581|
|Balinese saka calendar||749–750|
|Chinese calendar||丁未年 (Fire Goat)|
3524 or 3464
— to —
戊申年 (Earth Monkey)
3525 or 3465
|- Vikram Samvat||884–885|
|- Shaka Samvat||749–750|
|- Kali Yuga||3928–3929|
|Japanese calendar||Tenchō 5|
|Minguo calendar||1084 before ROC|
|Seleucid era||1139/1140 AG|
|Thai solar calendar||1370–1371|
954 or 573 or −199
— to —
955 or 574 or −198
Year 828 (DCCCXXVIII) was a leap year starting on Wednesday (link will display the full calendar) of the Julian calendar.
- Siege of Syracuse: The Muslims under Asad ibn al-Furat defeat a Byzantine relief army sent from Palermo, and backed by a Venetian fleet led by Giustiniano Participazio. Al-Furat decides to break off the siege at Syracuse, as his forces suffer greatly from lack of food. Later he dies during an outbreak of an epidemic.
- Summer – Euphemius, Byzantine admiral, is murdered by emissaries from the Byzantine garrison at Castrogiovanni, which is besieged by the Muslims. Threatened by Byzantine reinforcements arriving from Constantinople, the survivors burn their ships and retreat overland westward to Mazara del Vallo.
- Al-Andalus: The city of Merida (modern Spain) rises twice in one year against the Umayyad Emirate.
- Kydonia, on the northwest coast of Crete, is destroyed by Saracen pirates (approximate date).
- Alcamo in Sicily is founded by the Muslim commander al-Kamuk (approximate date).
- In the capital of Chang'an, a powerful court eunuch orders 50 wrestlers to arrest 300 commoners over a land property dispute in Northwest Chang'an, whereupon a riot breaks out in the streets.
- The occupation of Pueblo Bonito begins.
- Relics of Mark the Evangelist are stolen from Alexandria (controlled by the Abbasid Caliphate) by two Venetian merchants, and brought to Venice.
- At the instigation of Adalram, archbishop of Salzburg, the first Christian church in Central and Eastern Europe is built in Nitra, Pannonia.
- A Coptic revolt breaks out in Egypt (approximate date).
- Ali al-Hadi, 10th Shia Imam
- Al-Dinawari, astronomer and grammarian (d. 889)
- Carloman of Bavaria, Frankish king (or 830)
- Ibn Qutaybah, Muslim scholar (d. 889)
- Yantou Quanhuo, Chinese Chan master (d. 887)
- Asad ibn al-Furat, Muslim jurist and theologian (b. 759)
- Euphemius, Byzantine admiral and usuper
- Ibn Hisham, Muslim historian (or 833)
- Idriss II, Muslim emir of Morocco (b. 791) 
- Nikephoros I, patriarch of Constantinople
- Talha ibn Tahir, Muslim governor
- ^ Treadgold (1988), pp. 253–254.
- ^ Vasiliev (1935), pp. 83–84.
- ^ Rucquoi, Adeline (1993). Histoire médiévale de la Péninsule ibérique. Paris: Seuil. p. 86. ISBN 2-02-012935-3.
- ^ Donald M. Nicol, Byzantium and Venice: A study in diplomatic and cultural relations (Cambridge: University Press, 1988), p. 24.
- ^ Klein, "Adalram".
- ^ Gilbert Meynier (2010) L'Algérie cœur du Maghreb classique. De l'ouverture islamo-arabe au repli (658-1518). Paris: La Découverte; p. 28.