A paver patio is only as good as what is under it. The base does the work; the pavers are the surface.
The layers
From the bottom up: compacted subgrade, a gravel base, a bedding layer of sand, then the pavers. Edge restraints hold it all in place.
Typical depths
A common build is about 4 inches of compacted gravel base, roughly 10 cm, and 1 inch of bedding sand, about 2.5 cm. Heavier use or poor soil calls for a deeper base.
Estimating the materials
Work out the patio area, then calculate the gravel and sand as volumes at those depths. The paver calculator gives the paver count plus both base volumes in one step.