Here is a list of the planets in order from smallest to largest:

1. Mercury: Radius = 2,440 km

2. Mars: Radius = 3,390 km

3. Venus: Radius = 6,052 km

4. Earth: Radius = 6,378 km

5. Neptune: Radius = 24,764 km

6. Uranus: Radius = 25,362 km

7. Saturn: Radius = 60,268 km

8. Jupiter: Radius = 71,492 km

Pluto, which used to be considered a planet, is actually a dwarf planet. It is much smaller than the other planets, with a radius of only 1,184 km.