New Jersey is about 11 times smaller than Belarus.

Belarus is approximately 207,600 sq km, while New Jersey is approximately 19,211 sq km, making New Jersey 9.25% the size of Belarus. Meanwhile, the population of Belarus is ~9.4 million people (621,611 fewer people live in New Jersey).
Tip: This to-scale comparison of Belarus vs. New Jersey uses the Mercator projection, which distorts the size of regions near the poles.