Alaska's mountains add 11,000 square miles. Still under 2%.
Three honest answers to "how big is this state" — total area, land only (water subtracted out), and true surface area if every slope were ironed flat. They don't agree, but not by as much as you'd think.
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Michigan and Hawaii are both about 41% water. Michigan's share is the Great Lakes; Hawaii's is the ocean and reef claimed within its state boundary. Either way, Michigan's water alone — 40,175 square miles of it — covers more area than the entire land mass of Kentucky. Rhode Island is next at 33%, almost entirely Narragansett Bay.
Ironing every slope flat barely moves the number. Nobody publishes a state's true 3D surface area, so this map computes it: a global elevation grid, sliced into roughly half-kilometer cells, each tilted cell's real area worked out from its slope, then summed by state. Alaska gains the most — about 11,000 extra square miles, more than the entire state of Massachusetts — but that's still under 2% of Alaska's footprint. Washington, Idaho, and California are the next-most-inflated, all still under 1.5%. Most states gain a few hundredths of a percent. Even a state that looks dramatically vertical from the ground is, from directly overhead, still mostly close to flat.
Total/land/water area: U.S. Census Bureau, via Wikipedia's list of states by area. Surface area: computed from the GEBCO_2025 global elevation grid (15 arc-second resolution, ~460m cells) — for each land cell, true area = flat area × √(1 + slope²), summed by state via point-in-polygon against state boundaries. Coarser than the terrain's real roughness, so treat these ratios as a floor, not a ceiling.