Nauru is about 4,900 times smaller than Kentucky.

Kentucky is approximately 102,896 sq km, while Nauru is approximately 21 sq km, making Nauru 0.02% the size of Kentucky. Meanwhile, the population of Kentucky is ~4.3 million people (4.3 million fewer people live in Nauru).
Tip: This to-scale comparison of Kentucky vs. Nauru uses the Mercator projection, which distorts the size of regions near the poles.