Paver calculator

The paver count itself is simple area division. A 4 by 8 inch paver covers 0.222 square feet, so a 20 by 10 foot patio — 200 square feet — takes 900 pavers before waste. Add 5 percent for straight runs and 10 percent if you have curves or a diagonal pattern, which forces far more cutting.

What trips people up is everything under the pavers. That same 200 square foot patio needs 2.96 cubic yards of base gravel — about 4.1 tons — plus 0.62 cubic yards of bedding sand. Those two layers usually cost more and weigh more than the pavers, and they're what most first-time estimates leave out entirely. Note that the base figure is the loose volume you order: crushed base compacts about 20 percent, so 2.47 cubic yards in place takes 2.96 delivered.

Bedding sand is one inch, and only one inch. It's a screeded leveling layer, not a way to fix a bad base. A thicker bed lets pavers settle unevenly under load no matter how carefully you compact it, and the result shows up as ruts and rocking within a season. Use coarse concrete sand, never mason sand or play sand.

There is a third sand in this job, and it is not the bedding sand. Once the pavers are down and compacted, the joints between them get filled from the top, and what goes in there is polymeric sand: a jointing sand with a binder that sets when you mist it. It locks the field together, keeps weeds down and stops the joints washing out in rain. Ordinary sand in the joints washes away by the second season. Polymeric sand is sold by the bag with a coverage figure that depends on your joint width and paver thickness, so read the bag rather than scaling it from the area.

Base depth is what separates a patio from a driveway. Four inches of compacted crushed base is enough for foot traffic; a driveway wants 8 to 12 inches, placed and compacted in lifts of no more than 4 inches each. And every paved area needs an edge restraint around the perimeter — without it the outer courses creep outward and the field loosens from the edges inward.