A person weighing 50kg (110lbs) on Earth would weigh 19kg (42 lbs) on Mars. This is because the gravitational force on Mars is only 38 percent that of the gravitational force on Earth.
To find the equivalent of an Earth weight on Mars, multiply the Earth weight by 0.38. A man who weighs 200lbs (90kg) on Earth would weigh 76lbs (34kg) on Mars. The weight on Mercury is the same as the weight on Mars. Finding the equivalent weight on Jupiter, however, requires multiplying the Earth weight by 2.34 because the gravitational force is 2.34 times greater on Jupiter than on Earth. A person weighing 50kg (110lbs) would weigh 117kg (257lbs) on Jupiter, while a person weighing 200lbs (90kg) would weigh 468lbs (212kg) there.