Missouri is about 312 times bigger than Isle of Man.

Isle of Man is approximately 572 sq km, while Missouri is approximately 178,414 sq km, making Missouri 31,091% larger than Isle of Man. Meanwhile, the population of Isle of Man is ~91,382 people (5.9 million more people live in Missouri).
Tip: This to-scale comparison of Isle of Man vs. Missouri uses the Mercator projection, which distorts the size of regions near the poles.