love.physics.getMeter
Returns the meter scale factor.

All coordinates in the physics module are divided by this number, creating a convenient way to draw the objects directly to the screen without the need for graphics transformations.

It is recommended to create shapes no larger than 10 times the scale. This is important because Box2D is tuned to work well with shape sizes from 0.1 to 10 meters.
scale = love.physics.getMeter()
scale number The scale factor as an integer.