Lithuania is around the same size as Croatia.

Croatia is approximately 56,594 sq km, while Lithuania is approximately 65,300 sq km, making Lithuania 15% larger than Croatia. Meanwhile, the population of Croatia is ~4.2 million people (1.5 million fewer people live in Lithuania).
Tip: This to-scale comparison of Croatia vs. Lithuania uses the Mercator projection, which distorts the size of regions near the poles.