Divide the area by the space one paver takes, joint included, then add 10% for cuts. A 10 × 12 ft patio of 4 × 8 in pavers with ⅛ in joints is 120 sq ft at 4.3 pavers a square foot: 516 pavers, 568 with the extra. Under them go 4 in of compacted base (about 3.2 tons of gravel) and 1 in of bedding sand (20 bags of 0.5 cu ft), so you dig about 7⅜ in.
How to measure for pavers
- Patio or walkway: measure the length and the width inside the edge restraint. For an L-shaped patio, run each rectangle and add them up, or enter the area.
- Round patio or fire pit pad: measure across the middle and pick Circle.
- Your paver: enter the size on the label or the maker’s sheet. A paver sold as 4 × 8 is often a little smaller, which leaves room for the joint.
- Joint: CMHA, the industry body that took over from ICPI, keeps joints between 1/16 and 3/16 in; most pavers have spacer nubs that set it for you. The calculator starts at ⅛ in.
The math, with your numbers
These lines follow whatever you typed into the calculator above.
The base is spread a third deeper than it ends up, because tamping squeezes it down; the gravel calculator explains the 4/3 and the 1.62 tons a yard. Pavers and bags are rounded up.
How many pavers per square foot?
| Paver | Per sq ft, ⅛ in joints | For 100 sq ft | With 10% extra |
|---|---|---|---|
| 4 × 8 in | 4.30 | 430 | 473 |
| 6 × 6 in | 3.84 | 384 | 423 |
| 6 × 9 in | 2.58 | 258 | 284 |
| 12 × 12 in | 0.98 | 98 | 108 |
| 16 × 16 in | 0.55 | 56 | 61 |
| 24 × 24 in | 0.25 | 25 | 28 |
Our arithmetic: 144 ÷ ((length + joint) × (width + joint)). With 3/16 in joints a 4 × 8 paver works out to 4.20 a square foot; with 1/16 in, 4.40.
How deep should the base be?
CMHA’s construction guide sets the base by what goes over it and the soil under it:
| Use | Base, compacted | Bedding sand | Pavers |
|---|---|---|---|
| Patios, walks, pedestrian areas | 4 in minimum | 1 in | 2⅜ in (60 mm) |
| Residential driveways | 6 in minimum | 1 in | 2⅜ in (60 mm) |
Source: CMHA Tech Note PAV-TEC-002. The minimums are for well-drained soil; CMHA says colder climates and wet or weak soils need a thicker base. This Old House uses 4 to 6 in for pedestrian areas and 6 to 8 in for driveways.
The base is crushed stone with fines that packs hard when you compact it; our paver base guide covers the material and the compaction. CMHA wants it compacted in even layers, with a finished surface no more than ⅜ in off a 10 ft straightedge, because the sand above can’t make up for dips: they show through the pavers later.
Bedding sand and joint sand
Bedding sand goes between the base and the pavers. CMHA calls for washed concrete sand (ASTM C33), spread and screeded to a loose 1 in, not stone dust or mason sand, which drain and pack unevenly. QUIKRETE sells it in 0.5 cu ft bags. Its table gives 34 bags for 100 sq ft at 2 in, the same arithmetic the calculator uses (100 × 2/12 ÷ 0.5 = 33.3, so 34); at 1 in it’s 17.
Joint sand is swept into the gaps after the pavers are laid and compacted. It can be finer sand or polymeric sand, which hardens once it is wetted. Alliance Gator puts its Gator Maxx G2 at about 65 to 85 sq ft per 50 lb bag for joints of ⅛ to ⅜ in, and 22 to 42 sq ft for wide joints of ¾ to 1¼ in; the calculator shows that range for your area.
How deep to dig for pavers
Add the three layers: paver thickness, 1 in of sand and the base. For 2⅜ in pavers on a 4 in base that’s 7⅜ in below the finished surface; on a driveway’s 6 in base, 9⅜ in. This Old House digs 6 to 8 in for pedestrian areas and 8 to 12 in for driveways.
Slope the surface so water runs off. CMHA asks for at least 1.5%, and This Old House uses 1 in for every 4 ft, about 2%: on a 12 ft patio, 3 in lower at the far edge, away from the house.
Set the edge restraint before the sand goes down. CMHA wants at least 1 in of it touching the side of the pavers, and a paver patio without one spreads at the edges.
Questions people ask
How many pavers do I need?
Divide the area by the space one paver takes with its joint, then add 10%. A 4 × 8 in paver with ⅛ in joints covers 33.5 sq in, so 4.3 pavers a square foot: 430 for 100 sq ft, 473 with the extra.
How much paver base do I need?
Area × compacted depth in feet × 4/3, divided by 27 for cubic yards. A 120 sq ft patio with a 4 in base needs about 2 cu yd of loose gravel, about 3.2 tons.
How much sand do I need for pavers?
For 1 in of bedding sand, one 0.5 cu ft bag covers 6 sq ft: 17 bags for 100 sq ft. Joint sand is extra; polymeric sand covers about 65 to 85 sq ft a 50 lb bag with narrow joints.
How deep should a paver base be?
At least 4 in compacted for patios and walks, and 6 in for driveways, on well-drained soil (CMHA). Wet, weak or frost-prone soils need more.
How much extra pavers should I buy?
This Old House adds 10 to 15% for cuts and breakage. Keep a few spares to replace a broken paver later.
Sources
- Concrete Masonry & Hardscapes Association (formerly ICPI), Tech Note PAV-TEC-002, Construction of Interlocking Concrete Pavements
- This Old House, How to install pavers
- QUIKRETE, HardScapes Paver Installation sheet (0.5 cu ft bags, bags per area)
- Alliance Gator, Gator Maxx G2 technical data sheet (coverage per 50 lb bag)
- Penn State Center for Dirt and Gravel Road Studies, Driving Surface Aggregate tech bulletin (spread a third more than the compacted depth; 1.62 tons per loose cubic yard)
Checked October 12, 2026. Metric values are converted from feet, inches and US tons.