Houston is about 4.3 times bigger than Saint Vincent and the Grenadines.

Saint Vincent and the Grenadines is approximately 389 sq km, while Houston is approximately 1,659 sq km, making Houston 326% larger than Saint Vincent and the Grenadines.
Tip: This to-scale comparison of Saint Vincent and the Grenadines vs. Houston uses the Mercator projection, which distorts the size of regions near the poles.