Uranus has 14.5 times the mass of Earth. Yet if you could somehow stand on its cloud tops, you would actually weigh 11% less than you do right now.
A planet's surface gravity is not determined by mass alone. According to Newton's law of universal gravitation, the gravitational force you feel on a planet's surface depends on two variables: the planet's mass and its radius. While gravity is directly proportional to mass, it is inversely proportional to the square of the radius. This means the distance from the center of the planet matters significantly more than the sheer amount of matter it contains.
When a planet gains mass, its physical size usually increases as well. If a planet's radius grows, you are pushed further away from its center of mass. Because the radius is squared in the gravity equation, a large increase in volume can easily overpower a substantial increase in mass.
Saturn is a perfect example of this dynamic. The gas giant contains 95 times more mass than Earth. However, because it is composed mostly of hydrogen and helium, it is far less dense, giving it a radius more than nine times that of Earth. Since you would be so far from Saturn's center of mass, its surface gravity is only 10.44 m/s²—barely stronger than Earth's 9.8 m/s².
This mathematical relationship is also why ultra-dense cosmic objects possess such extreme gravitational pulls. A neutron star has roughly the same mass as the Sun, but it is compressed into a sphere just 20 kilometers across. Because the radius is incredibly small, the surface gravity is billions of times stronger than Earth's. Ultimately, surface gravity is a contest between how much mass a celestial body has and how closely you can stand to the center of it.