According to NASA's StarChild site, Saturn has a density of 0.7 grams per cubic metre. The other three 'gas giants' are approximately twice as dense: Jupiter and Uranus 1.3, Neptune 1.6.
Each of the three innermost planets is almost eight times as dense as Saturn, and four times as dense as the other three gas giants – ranging from 5.2 (Venus) to 5.5 (Earth). The fourth (Mars) is somewhat less dense at 3.9 grams per cubic metre.
© Haydn Thompson 2019