There is a lot of debate as to what the largest dog breed actually is – if you consider the largest dog by weight and overall size then the winner is either the Saint Bernard or Mastiff, but if you consider the largest dog by height then it could be the Great Dane or Irish Wolfhound. However, where the debate truly heats up is in trying to determine which breeds are truly bigger than another as there can often be a lot of size variation within the breeds themselves.
For example, the Great Dane holds the record for the tallest breed, but on average Irish Wolfhounds are considered to be taller. Mastiffs and Saint Bernards are usually of a similar size but a large Saint Bernard can easily be much heavier than a Mastiff. When you take standard size requirements from the American Kennel Club into account, however, these are the top 10 largest dog breeds.