Miami is about 4.2 times smaller than Saint Vincent and the Grenadines.

Saint Vincent and the Grenadines is approximately 389 sq km, while Miami is approximately 92 sq km, making Miami 23.75% the size of Saint Vincent and the Grenadines.
Tip: This to-scale comparison of Saint Vincent and the Grenadines vs. Miami uses the Mercator projection, which distorts the size of regions near the poles.