# What's the proportion of Mars' surface compared to Earth's surface uncovered of water?

How does Mars surface compare to Earth's surface? Mars is quite smaller than Earth, but most Earth's surface is covered with water. I thought making the math could be relatively easy but Earth isnt a sphere and I dont know about Mars?

What's the proportion of Mars' surface compared to Earth's surface uncovered of water?

• The Wikipedia pages for Earth and Mars list the surface areas of these planets in the infoboxes, and for Earth it provides the amount covered by land and water. Do these pages help answer your question?
– user24157
Feb 17, 2019 at 19:59
• Earth's diameter is about 25 miles greater at it's equator than pole to pole, or 1 part in 400. That works out to a variation of 1 part in about 200 by surface area, so you can use spherical math and not be off by much. Like Earth, Mars is an oblate spheroid with a slightly larger equatorial bulge (higher ratio of angular momentum to gravity I would think or something). en.wikipedia.org/wiki/Equatorial_bulge If you want higher accuracy, you can use Oblate Spheroid surface area formulas. vcalc.com/wiki/vCalc/Oblate+Spheroid+-+surface+area Feb 17, 2019 at 20:25
• Relevant xkcd xkcd.com/1389 Feb 17, 2019 at 20:37
• @mistertribs I think so. Dont you want to answer? It's interesting (at least to me) to notice the surfarce of Mars is about the same as the land surfarce of Earth so colonizing Mars would add "another Earth" of potential lands (though I guess you cant set a base anywhere on Mars) Feb 17, 2019 at 23:57
• @Pablo, mistertribs is pointing out that it's a trivial calculation & you might enjoy doing it yourself. Feb 18, 2019 at 18:55