San Marino is about 1,523 times smaller than Indiana.

Indiana is approximately 92,895 sq km, while San Marino is approximately 61 sq km, making San Marino 0.07% the size of Indiana. Meanwhile, the population of Indiana is ~6.5 million people (6.4 million fewer people live in San Marino).
Tip: This to-scale comparison of Indiana vs. San Marino uses the Mercator projection, which distorts the size of regions near the poles.