Boston
232 km²
San Francisco
121 km²
USA
USA
Area Comparison
Boston is 1.9x larger than San Francisco
Population Comparison
Boston has 1.3x fewer people than San Francisco
In terms of area, Boston is 1.9x the size of San Francisco. Boston spans 232 km² (90 mi²) while San Francisco covers 121 km² (47 mi²) — a difference of 111 km².
To put Boston's size in perspective, its area of 232 km² is roughly the same size as Amsterdam. Meanwhile, San Francisco at 121 km² is about 1.2x the size of Paris (city proper).
Picture Boston another way: its area is large enough to fit about 32,000 American football fields, 110 times the area of Monaco, or 68 times the area of Central Park. For San Francisco, that's about 17,000 American football fields, 60 times the area of Monaco, or 35 times the area of Central Park.
Boston is the capital and most populous city of the U.S. state of Massachusetts. It serves as a cultural and financial center of New England, a region of the Northeastern United States. Boston has an area of 48.4 sq mi (125 km2) and a population of 675,647 as of the 2020 census, making it the third-most populous city in the Northeastern United States after New York City and Philadelphia.
Known as "Beantown", Boston covers 232 km² with a population of 0.7 million. The city was established in 1630. Boston is known for Fenway Park, Freedom Trail, Harvard University, among other attractions. The city's main transit system is the MBTA (The T).
Boston covers just 125 km2 yet serves as the cultural and financial heart of all New England
San Francisco, officially the City and County of San Francisco, is the fourth-most populous city in California and the 17th-most populous in the United States, with a population of 826,079 in 2025. Among U.S. cities with a population of 300,000 or more, San Francisco is ranked first by per capita income, second by population density, and sixth by aggregate income as of 2023.
Also known as "The City by the Bay", San Francisco has an area of 121 km² and is home to 0.9 million people. Its history stretches back to 1776. Visitors come for Golden Gate Bridge, Alcatraz Island, Cable cars, and much more. Getting around is easy with the BART & Muni.
San Francisco ranks first by per capita income among all US cities with 300,000+ residents as of 2023.
Looking beyond city limits, the Boston metropolitan area covers 11,700 km², which is 1.7x larger than greater San Francisco at 6,984 km². The Boston metro area is also more populous, with 4.9 million people compared to 4.7 million.
Boston has a population density of 2,931 people per km² — a moderately dense city. San Francisco, with 7,190 people per km², is a densely populated city. San Francisco is noticeably denser, packing 2.5 times more people per square kilometer.
Both Boston and San Francisco are in USA, making this a domestic size comparison that reveals how differently cities can develop within the same nation.
Boston has a humid continental climate while San Francisco experiences Mediterranean conditions. When it's noon in Boston, it's 9:00 AM in San Francisco — a 3-hour time difference.
Density Gap
San Francisco is 2.5x more densely populated
Time Difference
3 hours apart
History
Boston is ~146 years older
Boston covers 232 km². Cities with a similar urban footprint include Osaka (225 km²), Kuala Lumpur (243 km²), Amsterdam (219 km²), Helsinki (214 km²), or Edinburgh (259 km²).
San Francisco covers 121 km². Cities with a similar urban footprint include Vancouver (115 km²), Paris (105 km²), Miami (143 km²), Barcelona (101 km²), or Lisbon (100 km²).
The straight-line distance from Boston to San Francisco is 4,334 km (2,693 miles), with an estimated flight time of ~5h 36m.
Want to explore more? Compare city sizes for any two cities worldwide, or share your location live with friends.