New Caledonia is around the same size as New Jersey.

New Jersey is approximately 19,211 sq km, while New Caledonia is approximately 18,575 sq km, making New Caledonia 96.69% the size of New Jersey. Meanwhile, the population of New Jersey is ~8.8 million people (8.5 million fewer people live in New Caledonia).
Tip: This to-scale comparison of New Jersey vs. New Caledonia uses the Mercator projection, which distorts the size of regions near the poles.