Pavers per square foot, and why the nominal size is the right one to use
A 4 by 8 paver does not measure 4 by 8. It measures closer to 3-7/8 by 7-7/8, and the missing eighth is the joint. Laid tight, it modules to exactly 4 by 8, which is why the industry quotes coverage on the nominal size. Thirty-two square inches into 144 gives 4.5 pavers per square foot, and that is the number that comes out right on the pallet.
| Nominal size | Sq in | Pavers per sq ft |
|---|---|---|
| 4 x 8 | 32 | 4.50 |
| 6 x 6 | 36 | 4.00 |
| 6 x 9 | 54 | 2.67 |
| 8 x 8 | 64 | 2.25 |
| 12 x 12 | 144 | 1.00 |
| 12 x 24 | 288 | 0.50 |
| 16 x 16 | 256 | 0.5625 |
If you are laying natural stone rather than concrete pavers, the nominal trick does not apply, because the joint is deliberate and often 3/8 or more. Use the custom size field and enter the stone size plus the joint you intend to run.
Pattern waste is about the edges
Waste in a paver field is almost entirely cuts at the perimeter, so it scales with the perimeter, not the area. That means the percentage is worse on a small patio than a large one, and worse on a long thin walkway than a square. The figures used here are the common ones: 5 percent for running bond, stack bond and basketweave, where most edge cuts are straight and the offcut is often usable on the opposite side; 8 percent for 90 degree herringbone; and 12 percent for 45 degree herringbone, where every edge paver is a diagonal cut and the triangle you remove is almost never reusable.
These are working numbers rather than measured ones, and they assume a rectangular area. Add to them for anything with a curve, for a border course in a second colour where the field and border waste separately, and for an area under 100 square feet, where the perimeter-to-area ratio makes any percentage optimistic. Buy from one dye lot in one delivery. Concrete pavers from a later batch will not match, and the difference is obvious in daylight.
Base, bedding and joint sand are three different materials
They get confused constantly. The base is compacted crushed aggregate with fines in it, laid 4 inches deep for a pedestrian patio and 8 to 12 for a driveway, compacted in lifts of 3 or 4 inches. Bedding is one inch of coarse washed sand, screeded and never compacted before the pavers go on and never used to make up for a base that is out of level. Joint sand is what goes between the pavers afterwards, swept in and vibrated down, usually polymeric so it hardens and resists washout and weeds.
The quantities: base is area times depth divided by 12 for cubic feet, then divided by 27 for yards, then add roughly 20 percent because it compacts. Bedding at one inch over 320 square feet is 26.7 cubic feet, or about a cubic yard, which is around 1.35 tons. Joint sand comes from the joint geometry: a 1/8 inch joint on 4 by 8 pavers takes up about 4.6 percent of the surface, and through a 2-3/8 inch thick paver that is about 0.009 cubic feet per square foot of patio, so a 50 lb bag covers somewhere near 55 square feet.
That last figure is the one to check against your own bag, because printed coverage for polymeric sand spans a huge range and depends on joint width, paver thickness and how deep the joint actually is once the bedding has crept up. Under-buying joint sand is the cheapest mistake to fix on the day and the most annoying one to discover a month later, when the half-filled joints have already started shedding sand into the lawn.
Questions people ask
How many 4x8 pavers do I need per square foot?
Four and a half. A 4 by 8 paver is nominally 32 square inches, and 144 divided by 32 is 4.5. The actual paver is nearer 3-7/8 by 7-7/8 and the difference is the joint, which is why the nominal figure is the one that works out correctly on site. For a 200 square foot patio that is 900 pavers bare, or 945 at 5 percent waste for a running bond, or about 1,008 for a 45 degree herringbone.
How much waste should I allow for herringbone?
Around 10 to 15 percent for a 45 degree herringbone and about 8 for a 90 degree one, against 5 percent for running bond. The reason is that every paver meeting the edge in a 45 degree pattern is a diagonal cut, and the triangular offcut usually cannot be used anywhere else. Waste tracks the perimeter rather than the area, so a small or narrow area needs a higher percentage than a large square one. Curves push it higher again.
How deep does the base need to be under a patio?
Four inches of compacted crushed base is the common figure for a pedestrian patio on stable, well-drained ground. Six inches for a walkway that will see garden equipment, and 8 to 12 inches for a driveway. Clay subgrade and hard-freeze climates want more than the minimum, and the base has to be compacted in lifts of 3 to 4 inches rather than dumped and rolled once. Depth does not compensate for compaction. A thick loose base settles just as badly as a thin one.
Can I skip the bedding sand and lay pavers straight on gravel?
No. The one inch of screeded coarse sand is what lets each paver seat individually and share load with its neighbours, and it is what you set the final level with. Laying on gravel gives you point loading on the aggregate and a surface you cannot get flat. The one thing to avoid in the other direction is going thicker: more than about an inch of sand consolidates unevenly under traffic and the patio goes wavy within a season.
Do I need edge restraint?
On anything that is not enclosed by a wall or a slab, yes. A paver field spreads sideways under use, the perimeter pavers move out, the joints open, and the sand washes out of them. Plastic or aluminium edge restraint spiked into the base is the usual solution, and it needs the base to extend at least 6 inches past the paver edge to have something to spike into. The rough perimeter figure in the results is a placeholder. Measure the actual open edges, because a patio against a house needs restraint on three sides, not four.