Yellowstone National Park is about 28 times smaller than Wyoming.

Wyoming is approximately 251,489 sq km, while Yellowstone National Park is approximately 8,983 km² (3,469 sq mi), making Yellowstone National Park 3.57% the size of Wyoming.
Tip: This to-scale comparison of Wyoming vs. Yellowstone National Park uses the Mercator projection, which distorts the size of regions near the poles.
Our free app, MapSize by MyLifeElsewhere — compare any two places, to scale on your mobile device.