With an area of 1,648,000 square kilometers, Iran is among twenty biggest countries in the world. Iran is located in southwestern Asia, and shares its entire northern border with the former Soviet Union states. This border extends for more then 2,000 kilometers, including nearly 650 kilometers of water along the southern shore of the Caspian Sea. Iran's western borders are with Turkey in the north and Iraq in the south. In the east lie Afghanistan on the north and Pakistan on the south. To the south, a long coastline borders the Persian Gulf and Oman Sea.

Iran consists of rugged, mountainous rims surrounding high interior basins. The main mountain chain is the Zagros Mountains, exceeding from northwest to southeast. The center of Iran consists of several closed basins that collectively are referred to as the Central Plateau.