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The magnitude of the electrostatic force between two point charges is directly proportional to the magnitudes of each charge and inversely proportional to the square of the distance between the charges.

For calculating the direction and magnitude of the force simultaneously, one will wish to consult the full

${\displaystyle {\vec {F}}={\frac {1}{4\pi \epsilon _{0}}}{\frac {q_{1}q_{2}}{|{\vec {r}}|^{3}}}{\vec {r}}={\frac {1}{4\pi \epsilon _{0}}}{\frac {q_{1}q_{2}}{|{\vec {r}}|^{2}}}{\hat {r}}}$

where ${\displaystyle {\vec {F}}}$ is the electrostatic force vector, ${\displaystyle q_{1}}$ is the charge on which the force acts, ${\displaystyle q_{2}}$ is the acting charge, ${\displaystyle {\vec {r}}={\vec {r_{1}}}-{\vec {r_{2}}}}$ is the distance vector between the two charges, ${\displaystyle {\vec {r_{1}}}\ }$ is position vector of ${\displaystyle q_{1}}$, ${\displaystyle {\vec {r_{2}}}\ }$ is position vector of ${\displaystyle q_{2}}$, ${\displaystyle {\hat {r}}}$ is a unit vector pointing in the direction of ${\displaystyle {\vec {r}}}$, and ${\displaystyle \epsilon _{0}}$ is a constant called the permittivity of free space.

This vector equation indicates that opposite charges attract, and like charges repel. When ${\displaystyle q_{1}q_{2}\ }$ is negative, the force is attractive. When positive, the force is repulsive.