The Friday File: By square miles (mi2) Vatican City is the smallest country on Earth at 0.19 mi2. Coming in a distant second at roughly four times the size is Monaco at 0.78 mi2. Next comes the southwestern Pacific Ocean nation of Nauru at 8.1 mi2. The west-central Pacific Ocean Island nation of Tuvalu is fourth smallest at 10 mi2. For comparative purposes, mammoth-sized RI clocks in at 1,214 mi2.