There is much debate as to who won and lost the War of 1812. While most believe that 
the British won and the United States lost the war, there is even debate among those who answered this question. Below are the full arguments on both sides.  
  The British won due to the fact that they completed their objectives;  defend Canada by killing the Americans who tried to invade. 
 American Deaths:11,300 killed, wounded or missing in action. 
 British Deaths: 8,600 killed, wounded or missing in action. 
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 I would also like to add that Britain won the last battle between the  two countries - "Battle of Fort Bowyer" and that during the time of this  war Britain was also involved in the napoleon war. The Americans having  failed all their objectives, forfeited and wanted to sign a peace  treaty. 
 Additional answer: I'd like to add to his slightly. I am in Canada,  where most Canadians claim to have won the war due to the American  failure to capture Canada. I, however, look at it from this point of  view: The British were forced to give up all the land gains they'd made  during the war (true, the Americans also had to give back land, but it  was not nearly as large an area). As well, the Americans were granted  fishing rights in the St Lawrence river, which had previously been  solely British. But lost the right to place warships in the great lakes.  I believe it was strategically an British victory, as they successfully  achieved their sole purpose. 
 Another Answer: The Americans had their fighting rights in the Maritimes  and Great lakes taken away shortly after the war, and not returned  until the 1850's. Also, most of the US war aims were never achieved. The  returning of territory to the US does not mean that strategically the  US won, if that were the case, then the British/Canadians won the war  while the US won the peace treaty. Although the US had numerical  superiority during the war, the British had more experienced commanders  and soldiers for the most part in the early part of the war and by the  time the American troops could fight the British on even terms, the  British had sent thousands of additional battle trained troops from  Europe in 1814. Overall it may be a stalemate militarily, but  strategically and politically, if that was true, then the Korean Wars  and the Vietnam War, up until the Americans left were also draws. 
 The Americas didn't win. The objective was to first take Upper Canada  which they couldn't do. As I read the stats The Canadians/British  controlled more lakes and rivers and killed more Americans. Plus America  retreated back to America burning some villages on their way out.  That's not winning, that's being a poor loser. No matter which way one  looks at it the Americas objective was plain and simple to take over  Canada and they retreated. strategically stand point they took more  weapons when more British troops arrived they never returned. It's A  Canadian win because this is not the first time America had tried to  invade Canada and it was also not the first time America had failed.