Why is electromagnetic force greater then gravitational force?

Both the electrostatic and gravitational forces are directly proportional to the charge and mass of the objects, respectively.

In terms of math,

additionally

Since electrons and other atomic-scale objects have relatively large charges but little masses, electromagnetic forces predominate.

Gravitational forces predominate because macroscopic objects, like stars, have relatively little net charge overall relative to their massive mass.

The electromagnetic force is stronger than the gravitational force because it is mediated by photons, which have no mass and can travel at the speed of light, while gravity is mediated by hypothetical particles called gravitons, which are thought to be massless but have not been observed yet. Additionally, electromagnetic forces involve charged particles, which can be both positive and negative, leading to stronger interactions at short distances compared to the universal attraction of gravity.