It's important to clarify that we're talking about the planets in our solar system, as there are countless planets beyond.

Here are the 4 biggest planets in our solar system in order of size (largest to smallest):

1. Jupiter: The largest planet in our solar system, a gas giant with a diameter of 86,881 miles (139,822 kilometers).

2. Saturn: Another gas giant, Saturn is known for its beautiful rings. It has a diameter of 72,367 miles (116,464 kilometers).

3. Uranus: An ice giant, Uranus has a diameter of 31,518 miles (50,724 kilometers).

4. Neptune: Also an ice giant, Neptune has a diameter of 30,599 miles (49,528 kilometers).