The multi-layer anatomy of a paver patio
A professional interlocking concrete paver installation is built from the ground up in three primary layers: a compacted gravel subbase (typically 4 inches for pedestrian areas, 6 to 8 inches for driveways), an uncompacted 1-inch bedding layer of coarse concrete sand (ASTM C33), and the pavers themselves (standard 2-3/8 inch or 60 mm thick).
Total excavation depth should equal the sum of all layers—typically 7-1/4 to 7-1/2 inches below finished grade for a standard backyard patio. Skimping on excavation or base depth leads to uneven settlement, water pooling, and shifting edges after winter freeze-thaw cycles.
How do you calculate square footage from feet and inches?
Tape measures read in feet and inches, but area formulas require decimal feet. Divide any inch measurement by 12 before multiplying length by width, then divide square feet by 9 when ordering carpet or turf sold by the square yard:
where:
- L_ft, W_ft – Whole feet measured along the room or slab length and width;
- L_in, W_in – Extra inches converted to decimal feet (6 in = 0.50 ft, 3 in = 0.25 ft); and
- Area_sq ft – Net surface area in square feet. Convert area into 4×8 panels with the plywood sheet calculator or slab yardage with the concrete calculator.
Common paver sizes and square footage coverage
Paver counts depend on the unit's face dimensions. Convert dimensions from inches to square feet to determine units per square foot before applying your cutting allowance.
| Paver Style & Dimensions | Individual Area (sq ft) | Pieces per Sq Ft | Pieces for 100 sq ft (+10%) |
|---|---|---|---|
| 4 × 8 in standard brick | 0.222 sq ft | 4.50 units | 495 pavers |
| 6 × 6 in square paver | 0.250 sq ft | 4.00 units | 440 pavers |
| 6 × 9 in cobble paver | 0.375 sq ft | 2.67 units | 294 pavers |
| 12 × 12 in patio stone | 1.000 sq ft | 1.00 unit | 110 pavers |
| 16 × 16 in stepping stone | 1.778 sq ft | 0.56 units | 62 pavers |
| 24 × 24 in architectural slab | 4.000 sq ft | 0.25 units | 28 pavers |
Worked example: 10 ft by 10 ft backyard patio
For a 10 ft × 10 ft patio (100 sq ft) using popular 4 × 8 in pavers and standard 4-inch gravel base:
At 4.5 pavers per square foot, base count is 450 units. Adding 10% for edge cuts, border soldier courses, and broken pieces gives 495 pavers to order.
For subbase materials: 100 sq ft at 4 inches depth is 33.3 cu ft (1.23 cu yd) of crushed aggregate. Factoring 1.4 tons/yd³ and a 15% vibratory compaction loss requires ~2.0 tons of road base gravel. The 1-inch bedding sand layer requires 8.3 cu ft (0.31 cu yd), weighing ~0.4 tons. Perimeter edge restraint equals 40 linear feet (2 × (10 + 10)).
| Project Layer | Calculated Volume / Quantity | Recommended Order |
|---|---|---|
| Surface pavers (4×8 in) | 450 base units | 495 pavers (with 10% waste) |
| Crushed gravel base (4") | 1.23 cu yd (33.3 cu ft) | ~2.0 US short tons (~3,960 lbs) |
| Bedding sand (1" screed) | 0.31 cu yd (8.3 cu ft) | ~0.4 US short tons (~800 lbs) |
| Perimeter edge restraint | 40 linear feet | 40 ft rigid edging + 25 spikes |
| Polymeric joint sand | 100 sq ft surface area | 1 to 2 bags (50 lb bags) |
Laying patterns and waste factor guidelines
Simple running bond or stacked bond patterns parallel to patio borders generate very little waste—around 5% to 8%.
Herringbone patterns (45° or 90°) provide superior interlock against vehicular rotation but require diagonal perimeter cuts along all four sides. Always order 10% to 15% extra pavers for herringbone layouts or curved walkways with radius cuts.
Subbase compaction checklist
- Excavate native soil and slope the subgrade away from your house foundation by at least 1/4 inch per linear foot (1% to 2% drop) for positive drainage.
- Lay a commercial woven geotextile separation fabric over native soil before dumping gravel to stop aggregate sinking into clay or wet subsoil.
- Compact the gravel base in maximum 2-inch lifts with a heavy plate compactor; tamp in overlapping passes until the base does not yield underfoot.
- Never tamp or walk directly on the 1-inch sand bedding prior to placing pavers; screed it between two 1-inch conduit pipes.
- Sweep dry polymeric sand into joints after laying pavers, run the plate compactor (with a protective pad) over the pavers to lock joints, and mist with water according to manufacturer directions.