Bolivia
slightly less than three times the size of Montana

Bosnia and Herzegovina
slightly smaller than West Virginia

Botswana
slightly smaller than Texas

Bouvet Island
about 0.3 times the size of Washington, DC

Brazil
slightly smaller than the US

British Indian Ocean Territory land area is about 0.3 times the size of Washington, DC

British Virgin Islands
about 0.9 times the size of Washington, DC

Brunei
slightly smaller than Delaware

Bulgaria
slightly larger than Tennessee

Burkina Faso
slightly larger than Colorado