If you have a regular hexagon, and you know the length of a side then you can find the area of both.
the area of the hexagon (using the length of one of its sides) is:
(3s²√3)/2 sq.units, where s is the length of the side.
The largest circle that can be inscribed will have a radius of (s√3)/2 so its area will be:
(3πs²)/4 sq. units.
You can also now find the amount of waste by subtracting the area of the circle from the area of the hexagon.
hope that helps.