Gravitational Fields

The gravity of Earth, which is denoted by g, refers to the acceleration that the Earth imparts to objects on or near its surface due to gravity. 

A perfect sphere of uniform density, or whose density varies solely with distance from the centre (spherical symmetry), would produce a gravitational field of uniform magnitude at all points on its surface, always pointing directly towards the sphere's centre. The Earth is not a perfect sphere, but is slightly flatter at the poles while bulging at the Equator: an oblate spheroid. Also air resistence and some other effects are reduces or increases the gravitational acceleration of earth. 

This widget give the values of gravitational field (Gravity) based on the location.