Been doing a little star gazing lately (no not on E!), and found this helpful guide to planets apparent size. The chart breaks down how much magnification it would take to make each planet appear the same size as the moon to the naked eye. These numbers are “best case” since they are when the planet is in opposition to Earth (closest in relative orbits).

Mercury 250x
Venus 75x
Mars 100x (ave)
Jupiter 40x
Saturn 100x
Uranus 500x
Neptune 750x
Pluto 400x (just to be visible)