In game map info.

I’m an avid hardcore player. I love the TTK and the lack of hud making for more realistic gameplay. I want to use the mortars or be able to range for launchers without lock on. I see grid squares on the in-game map but no legend telling you the scale of the map or the distance the grid squares represent so it makes ranging near impossible other than just by “eye-balling” the distance to target. Does anyone know what the grid squares represent if they are even an actual representation and not just for aesthetics. Are they the same across all maps or vary depending on the map size?