Yellowstone National Park is about 3 times bigger than Yosemite National Park.

Yosemite National Park is approximately 3,027 km² (1,169 sq mi), while Yellowstone National Park is approximately 8,983 km² (3,469 sq mi), making Yellowstone National Park 197% larger than Yosemite National Park.
Tip: This to-scale comparison of Yosemite National Park vs. Yellowstone National Park uses the Mercator projection, which distorts the size of regions near the poles.

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