Yellowstone National Park is about 1.9 times bigger than Grand Canyon National Park.

Grand Canyon National Park is approximately 4,863 km² (1,878 sq mi), while Yellowstone National Park is approximately 8,983 km² (3,469 sq mi), making Yellowstone National Park 85% larger than Grand Canyon National Park.
Tip: This to-scale comparison of Grand Canyon National Park vs. Yellowstone National Park uses the Mercator projection, which distorts the size of regions near the poles.

Compare further: Yellowstone National Park vs. Grand Canyon National Park

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