Another way of looking at the percentage of sand is to look at surface cover. Some deserts have a very high percentage of the ground covered by vegetation, organic debris from the vegetation, and a pebble pavement on top of finer soils. If you look at things this way, some deserts are covered by very little sand. Over 30% of the earth's land surface is classified as desert. ...sand covers only about 20 percent of World's deserts... hope my info helps =) It really depends on how you define desert (and what you define as desert).