Antarctica is the world’s largest desert because its interior receives extremely little precipitation.
A desert is defined by dryness, not by heat or sand. Much of Antarctica gets less than 200 millimetres of precipitation annually, and some inland areas receive far less. Most of that precipitation falls as snow, which accumulates because temperatures remain low enough to prevent widespread melting.
Antarctica is also Earth’s coldest, driest, and windiest continent. Its enormous ice sheet covers about 98% of the land and contains roughly 90% of the world’s fresh water in frozen form. The continent’s icy appearance can therefore make its desert classification seem surprising.
The Sahara is the largest hot desert, but it is not the largest desert overall. Antarctica’s desert area is commonly estimated at about 14 million square kilometres, making it larger than the Sahara and every other desert on Earth.