Solomon Islands is about 2.6 times bigger than Jamaica.

Jamaica is approximately 10,991 sq km, while Solomon Islands is approximately 28,896 sq km, making Solomon Islands 163% larger than Jamaica. Meanwhile, the population of Jamaica is ~2.8 million people (2.1 million fewer people live in Solomon Islands).
Tip: This to-scale comparison of Jamaica vs. Solomon Islands uses the Mercator projection, which distorts the size of regions near the poles.