Hyde Park, London is 7.2 times larger than Boston Common.
Area: 0 km2 calculated
Boston Common is a central public park in Boston, Massachusetts. It is sometimes erroneously referred to as the "Boston Commons". Dating from 1634, it is the oldest city park in the United States. Wikipedia
Area: 1 km2 calculated
Hyde Park is one of the largest parks in London, and one of the Royal Parks of London, famous for its Speakers' Corner. The park was the site of the Great Exhibition of 1851, for which the Crystal Palace was designed by Joseph Paxton. Wikipedia