San Mateo is about 216 times smaller than Ho Chi Minh City.

Ho Chi Minh City is approximately 6,773 sq km, while San Mateo is approximately 31 sq km, making San Mateo 0.46% the size of Ho Chi Minh City.
Tip: This to-scale comparison of Ho Chi Minh City vs. San Mateo uses the Mercator projection, which distorts the size of regions near the poles.
Our free app, MapSize by MyLifeElsewhere — compare any two places, to scale on your mobile device.