Saint Lucia is about 289 times smaller than Oklahoma.

Oklahoma is approximately 177,847 sq km, while Saint Lucia is approximately 616 sq km, making Saint Lucia 0.35% the size of Oklahoma. Meanwhile, the population of Oklahoma is ~3.8 million people (3.6 million fewer people live in Saint Lucia).
Tip: This to-scale comparison of Oklahoma vs. Saint Lucia uses the Mercator projection, which distorts the size of regions near the poles.