The Sahara desert stretches farther than the distance from New York to Los Angeles.
The boundaries of the Sahara are the Atlantic Ocean on the west, the Atlas Mountains and the Mediterranean Sea on the north, the Red Sea and Egypt on the east, and the Sudan and the valley of the Niger River on the south.
The Sahara Desert is (very roughly) about 4800km (roughly East-West), by 1800km (roughly North South)
3.6 million square miles, the Sahara absolutely is the biggest hot desert in the world, by a wide margin: It’s more than three times the size of the next biggest desert (the Great Australian Desert) and almost quadruple the size of the Arabian Desert.