A paver patio is a gravel structure with a decorative top. The pavers everyone shops for are the cheapest part to get right; the base layers below them decide whether the surface is still flat in five years. Here is what goes under a patio, in order, with the quantities for each layer.
Layer 1: excavation
Dig out about 7 inches for a foot-traffic patio: 4 inches of gravel base, 1 inch of bedding sand, and roughly 2 3/8 inches of paver. Slope the excavation about 1 inch per 8 feet away from the house so water drains off the finished surface. The soil you remove is roughly 0.65 cubic yards per 100 square feet per inch of depth, which is worth knowing before you promise to "just spread it in the yard."
Layer 2: compacted gravel base, 4 inches
The base is crushed stone with fines (often sold as crusher run, road base, or 3/4 minus), compacted in 2 inch lifts with a plate compactor. Round pea gravel does not lock together and is the wrong material here.
Quantity: area x 4/12, divided by 27 for cubic yards. A 12 x 12 patio needs about 1.8 cubic yards. The gravel calculator converts any size, and driveways need 6 to 10 inches instead of 4.
Layer 3: bedding sand, 1 inch
Coarse concrete sand, screeded flat over the compacted base with a pair of pipes and a straight board. This layer is for leveling only: it is 1 inch, not more, and it never gets compacted before the pavers go down.
Quantity: area x 1/12 / 27. That same 12 x 12 patio needs about 0.45 cubic yards; the sand calculator does the conversion and the bag math.
Layer 4: pavers
Count pavers by face area plus 5 to 10 percent waste for edge cuts. A 4 x 8 brick paver runs 4.5 per square foot, so a 12 x 12 patio is around 715 with waste. The paver calculator counts pavers and both base layers in one pass.
Layer 5: edge restraint and joint sand
Edge restraint (spiked plastic edging or a concrete curb) is non-negotiable; without it the field spreads and joints open. Finish by sweeping polymeric sand into the joints and misting it. A 50 lb bag of polymeric sand fills about 50 to 75 square feet of standard paver joints.
Get the two buried layers right, compact them properly, and the patio on top is straightforward. Skip them, and no paver, however premium, will stay where you put it.