The preparatory work is very important when lay paving slabs.
If it is wet where the paving slabs are to be laid you should dig deeper. You can fill with a draining macadam under the layer of base course. If you are careless with the preparatory work there is a risk of the paving slabs (due to ground frost) moving both horizontally and vertically. Chances that they will settle in the right position in the spring are very small.
Length x width = m2
m2 x thickness = m3
m3 x material's weight/m3 = Quantity metric tons material
The volume weight can vary between different delivery points