Oklahoma is about 311 times bigger than Isle of Man.

Isle of Man is approximately 572 sq km, while Oklahoma is approximately 177,847 sq km, making Oklahoma 30,992% larger than Isle of Man. Meanwhile, the population of Isle of Man is ~91,382 people (3.7 million more people live in Oklahoma).
Tip: This to-scale comparison of Isle of Man vs. Oklahoma uses the Mercator projection, which distorts the size of regions near the poles.