Jersey is about 166 times smaller than New Jersey.

New Jersey is approximately 19,211 sq km, while Jersey is approximately 116 sq km, making Jersey 0.6% the size of New Jersey. Meanwhile, the population of New Jersey is ~8.8 million people (8.7 million fewer people live in Jersey).
Tip: This to-scale comparison of New Jersey vs. Jersey uses the Mercator projection, which distorts the size of regions near the poles.