Boston is about 3.1 times smaller than Saint Vincent and the Grenadines.

Saint Vincent and the Grenadines is approximately 389 sq km, while Boston is approximately 124 sq km, making Boston 31.88% the size of Saint Vincent and the Grenadines.
Tip: This to-scale comparison of Saint Vincent and the Grenadines vs. Boston uses the Mercator projection, which distorts the size of regions near the poles.