You weigh about 0.5% to 1% less at the equator than at the North or South Pole.

The Earth is an oblate spheroid rather than a perfect sphere, a shape first theorized by Isaac Newton in his 1687 work 'Principia'. Because of the planet's rotation, the equatorial diameter is about 43 kilometers (27 miles) larger than the polar diameter. This means a person standing at the equator is roughly 21 kilometers farther from Earth's center of mass than someone at the poles.According to Newton's Law of Universal Gravitation, the force of gravity decreases as distance from the center of mass increases. This geometric difference accounts for about 0.33% of the weight change. The remaining difference comes from centrifugal force, which is strongest at the equator where the Earth rotates at roughly 1,670 kilometers per hour (1,037 miles per hour).At the poles, the rotational speed is effectively zero, so there is no centrifugal force to counteract gravity. At the equator, this outward force pulls you away from the center, opposing the downward pull of gravity. Combined, these two factors result in a total gravity acceleration of 9.780 meters per second squared at the equator compared to 9.832 meters per second squared at the poles.This phenomenon was famously confirmed by Jean Richer in 1672 during an expedition to Cayenne, French Guiana. He discovered that a pendulum clock calibrated in Paris ran slower near the equator because gravity was weaker. Today, the International Union of Geodesy and Geophysics uses these precise measurements to define the Geodetic Reference System used for GPS and satellite navigation.