1812 (MDCCCXII) was a leap year starting on Wednesday in the Gregorian calendar and a leap year starting on Monday in the Julian calendar.

• March 5 – Prussia and France sign the Treaty of Paris
• March 26 – The 1812 Caracas earthquake destroys Caracas in Venezuela.
• April 30 – Louisiana is admitted as the 18th U.S. state.
• June 18 – The War of 1812 between the United States, Canada and the United Kingdom begins.
• December 30 – Convention of Tauroggen is signed.
• The capital of Finland is moved from Turku to Helsinki.

for more information, see Category:1812 births.

• February 12 – Charles Dickens

for more information, see Category:1812 deaths.