The force of gravity experienced on the surface of Mars is only 38 percent as strong as the Earth's surface gravity. The weaker gravitational force of Mars is due to its smaller mass and lower density.
Mars is the fourth planet from the Sun and is similar to the Earth in many respects. The gravitational force of a planet is proportional to its mass, and Mars is much smaller than the Earth. The planet has a diameter that is equal to only about half of Earth's diameter, and it has only a tenth of the density of Earth. Thus, an object that would weigh 100 kg on Earth would weigh just 38 kg on Mars.