Mars vs Venus: size comparison
Mars: 6,779 km. Venus: 12,104 km. Both silhouettes are drawn at the same scale.
Size ratio: ×1.8
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
Venus
12,104 km
What is measured Diameter of Venus
It is nearly Earth's twin in size, at 12,104 km across.
Source : Wikipedia — Venus