About this calculator
This calculator estimates what a block-paved patio, path, or driveway needs: the number of pavers (with a separate cut-waste allowance) and pallets, the bedding sand and sub-base (crushed stone/gravel) volumes, both compacted (in place) and loose (to order), and the length and unit count of the edge restraint (kerbs or edging). The area can be a rectangle, an L, T, or U shape, a rectangle with an alcove, or a free-form outline built from rectangles.
Formula
area = true area of the chosen outline
perimeter = true perimeter of the chosen outline
pitch = (paver length + joint) × (paver width + joint)
pavers per m² = 1 m² / pitch
pavers excl. waste = ceil(area / pitch)
waste pavers = ceil(pavers excl. waste × waste% / 100)
total pavers = pavers excl. waste + waste pavers
pallets = ceil(total pavers / pavers per pallet)
bedding sand volume (compacted) = area × sand thickness
sub-base volume (compacted) = area × sub-base depth
bedding sand to order (loose) = compacted sand volume × sand factor% / 100
sub-base to order (loose) = compacted sub-base volume × sub-base factor% / 100
edge restraint length = perimeter − edge needing no restraint
edging units = ceil(edge restraint length / unit length)
Each paver "owns" its own face plus half the joint on every side, so the area one paver covers in the finished surface is exactly one pitch. Everything bought in whole units (pavers, pallets, kerbs) is rounded up.
The loose-to-compacted factor says how much loose material, as delivered, compacts down to one unit of finished layer: 100% means no allowance, 130% means 1.3 m³ loose for every 1 m³ compacted. The defaults (120% for bedding sand, 130% for sub-base) are rough estimates only.
Worked example
Defaults: 5 × 4 m rectangle, 200 × 100 mm pavers, 3 mm joints, 5% waste, 480 pavers per pallet, 30 mm bedding sand, 150 mm sub-base, loose-to-compacted factors 120% (sand) and 130% (sub-base), 1000 mm edging units, no edge against a wall.
area = 5 × 4 = 20 m² = 20,000,000 mm²
perimeter = 2 × (5 + 4) = 18 m
pitch = 203 × 103 = 20,909 mm² → 47.8 pavers per m²
pavers excl. waste = ceil(20,000,000 / 20,909) = ceil(956.5) = 957
waste pavers = ceil(957 × 5 / 100) = ceil(47.85) = 48
total pavers = 1005
pallets = ceil(1005 / 480) = ceil(2.09) = 3
bedding sand (compacted) = 20 m² × 0.030 m = 0.6 m³
sub-base (compacted) = 20 m² × 0.150 m = 3.0 m³
bedding sand to order (loose) = 0.6 × 120 / 100 = 0.72 m³
sub-base to order (loose) = 3.0 × 130 / 100 = 3.9 m³
edge restraint = 18 m → ceil(18 / 1) = 18 units
FAQ
How much cut waste should I allow for paving? The 5% default is an example for a simple rectangular area laid in a straight pattern. Curved or notched edges, many cuts around drains and manholes, and herringbone or diagonal patterns all need more. The figure is yours to set; it is not a normative value.
Is the sand and gravel volume what I should order? Order the loose volume, not the compacted one. The compacted volumes are the geometric volumes of the finished layers at the thickness you enter. Loose material delivered to site takes up more volume before compaction, so the calculator multiplies by the loose-to-compacted factor you set. The defaults are rough estimates: how much the material compacts depends on the product, its grading and moisture, and the compaction achieved. Ask the supplier for the factor (or the tonnage) for their product and enter it. If they sell by the tonne, convert with their loose bulk density; this calculator does not.
How deep should the sub-base be? That depends on the ground, drainage, frost, and whether vehicles will use the paving. 150 mm is only an example for a pedestrian patio. Driveways and weak or frost-susceptible soils need a deeper sub-base designed for the site.
Why is there an input for edge that needs no restraint? Where paving runs up to a building wall or an existing kerb, that side is already restrained. Enter its length and it is taken off the perimeter before edging units are counted.
Does the joint width change the paver count? Yes. A wider joint makes each paver cover slightly more area, so fewer pavers are needed per square metre. If the paver has spacer nibs and its stated size already includes them, set the joint to 0.
Assumptions and limits
No standard is cited. Paver product standards (for example EN 1338 for concrete paving blocks)
specify the product itself, not a quantity take-off, and the layer thicknesses for a given use
come from pavement design guidance this calculator does not apply. meta.standards is empty
on purpose.
All defaults (paver size, joint width, waste %, pavers per pallet, sand thickness, sub-base depth, edging unit length) are realistic examples, not normative values. Enter your product's data and the build-up designed for your site.
The bedding sand and sub-base volumes are first taken as compacted (in-place) layers at the entered thickness. The loose order volumes are those compacted volumes multiplied by the loose-to-compacted factors, rounded up. The default factors (120% for bedding sand, 130% for a crushed-stone sub-base) are rough, non-normative estimates, not taken from any standard or published table: the real factor depends on the material, its grading and moisture, how it is delivered, and how well it is compacted. Replace them with your supplier's figure. No additional waste or spillage allowance is added on top, and tonnage is not calculated. The layers are taken over the paved area only; extra width under kerbs, haunching concrete, and any excavation beyond the paved outline are not included. Jointing sand is not calculated.
The paver count is the area divided by the pitch, rounded up, plus the waste allowance. It does not lay out individual cut pieces. The plan drawing shows a stretcher-bond joint pattern clipped to the outline; for a large area the pattern is simplified to keep the drawing legible, and the counts never come from the drawing. The section drawing is a schematic strip with the layer thicknesses to scale.
The edge restraint length is the true perimeter of the outline (a notch adds its own edges) minus the length you mark as needing no restraint. Corner pieces and the fixing of the edging are not modelled.