Here are the planets in our solar system in order of size, from smallest to largest, based on diameter:

1. Mercury: 4,880 km

2. Mars: 6,779 km

3. Venus: 12,104 km

4. Earth: 12,742 km

5. Neptune: 49,528 km

6. Uranus: 51,118 km

7. Saturn: 120,536 km

8. Jupiter: 142,984 km