Iran ranks directly above Mongolia by total area in Wikipedia's country-area table. Iran is listed 17th at about 1,648,195 square kilometers, while Mongolia follows at 18th with approximately 1,564,116 square kilometers.
The ranking places Iran below Libya and above Mongolia. Iran's area spans a large, mountainous plateau between the Caspian Sea and the Persian Gulf, while Mongolia is the world's largest landlocked country and lies farther east between Russia and China. The gap between them is about 84,079 square kilometers, roughly the size of Austria.
Readers sometimes remember a different order because country-area rankings can vary by source, especially when disputed territories, inland waters, or different boundary conventions are counted. In this table, total area means land plus inland water within international boundaries and coastlines. It is not a ranking by population, usable land, or maritime exclusive economic zone.