Jupiter vs Mars: size comparison
Jupiter: 139,820 km. Mars: 6,779 km. Both silhouettes are drawn at the same scale.
Size ratio: ×21
Jupiter
139,820 km
What is measured Equatorial diameter of Jupiter
Its Great Red Spot is a storm wider than Earth.
Source : Wikipedia — Jupiter
Mars
6,779 km
What is measured Mean diameter of Mars
Mars has half Earth's diameter, yet as much dry land.
Source : Wikipedia — Mars