Paver & Interlocking Block Calculator
Pavers, base aggregate, bedding sand, joint sand and edging for any patio or drive.
Units and currency
Area to pave
Not paved inside it (planters, tree rings)
Pavers
Base and sand
Edge restraint
Block thickness by traffic (IS 15658)
| Traffic | Grade | Minimum thickness | Examples |
|---|---|---|---|
| Non-traffic | M-30 | 50 mm | Building premises, landscapes, public gardens and parks, domestic drives, paths and patios |
| Light traffic | M-35 | 60 mm | Pedestrian plazas, car parks, office driveways, housing colonies, rural roads with low traffic, residential roads |
| Medium traffic | M-40 | 80 mm | City streets, small and medium market roads, low-volume roads |
| Heavy traffic | M-50 | 100 mm | Bus terminals, industrial complexes, roads on expansive soils, factory floors, service stations |
| Very heavy traffic | M-55 | 120 mm | Container terminals, ports, dock yards, mine access roads, airport pavements |
Recommended minimum paver block thickness and grade from IS 15658:2006 Table 1 (grade = 28-day compressive strength in N/mm²).
Shopping list
| Item | Quantity | Price | Cost |
|---|---|---|---|
| Total of the prices entered | — | ||
About the Paver & Interlocking Block Calculator
Plan a paved patio, path or driveway in one go: how many pavers or interlocking concrete blocks to buy, and the compacted aggregate base, bedding sand, joint sand and edge restraint under and around them. Add the areas as rectangles, L-shapes, circles, triangles or typed areas, leave out planters or tree rings, enter the paver size (or the pieces per m² for shaped blocks) and the laying pattern, and the calculator gives a shopping list you can price line by line.
The layer thicknesses start from the guidance of the Concrete Masonry & Hardscapes Association (formerly ICPI) — and IS 15658 for block thickness by traffic — and every value can be changed.
How to use it
- Choose Metric or US units and the currency. Add each area to pave, and any areas left out inside it such as a planter.
- Enter the paver size, or switch to pieces per m² or ft² for zigzag and other shaped blocks. Set the joint width, the paver thickness and the laying pattern — its cutting allowance fills in.
- Choose what the base is for (patio, driveway or street) to fill in the compacted thickness — the base runs out past the edging by the same amount unless you change it — and check the bedding sand (25 mm / 1 in), densities and the joint-sand bag size.
- Enter the length of edges against walls or kerbs (they need no edging) and, if you like, the length of one edging piece. Type prices in the shopping list in the unit you buy in, then copy it or download it as CSV.
Examples
47.83 pavers per m² × 12 m² = 574 + 5% = 603 pavers. Base 100 mm, running 100 mm past the 14 m of edging: (12 + 14 × 0.1) m² × 0.1 m = 1.34 m³ compacted, 1.61 m³ loose (2.57 t). Bedding sand 25 mm: 0.3 m³ (480 kg). Joint sand about 50 kg. Edging 14 m.
4.30 pavers per ft² × 288 ft² + 15% = 1,424 pavers. Edging 72 ft − 12 ft along the garage = 60 ft = 8 pieces of 8 ft. A 6 in base running 6 in out under that edging: (288 + 60 × 0.5) ft² × 0.5 ft = 159 ft³ = 5.89 yd³ compacted.
20 − 0.79 = 19.21 m² to pave; edging 18 m − 5 m along the house + 3.14 m round the planter = 16.14 m.
1,950 + 5% = 2,048 blocks = 6 pallets
How it is calculated
- Pavers = area to pave × pavers per m² × (1 + allowance), rounded up. Pavers per m² = 1 ÷ ((length + joint) × (width + joint)).
- Base = (paved area + the length of edge restraint × how far the base runs out under it) × compacted thickness — not past edges held by a wall; the loose volume to order adds the compaction allowance, and the weight is loose volume × bulk density.
- Bedding sand = paved area × screeded thickness.
- Joint sand = paved area × the share of the surface that is joint × the paver thickness. The joint share is 1 − L × W ÷ ((L + j) × (W + j)); for pieces per m², each block is treated as a square of the same area.
- Edge restraint = the perimeter of the paved areas and of any cut-outs − the edges against walls or kerbs.
Base, bedding sand and joints (CMHA guidance)
The Concrete Masonry & Hardscapes Association's technical note PAV-TEC-002 (formerly ICPI Tech Spec 2, Construction of Interlocking Concrete Pavements) gives these starting points:
- Base after compaction: at least 4 in (100 mm) for sidewalks, patios and pedestrian areas and 6 in (150 mm) for residential driveways, over well-drained soils. Cold climates and wet or weak soils need thicker bases; residential streets need 8–10 in (200–250 mm) and an engineer should set the base for streets and heavy-duty paving. Spread and compact it in 4–6 in (100–150 mm) lifts.
- Base past the edging: where plastic or metal edging is spiked into the base, the base should extend beyond the edging by at least its own thickness — a 6 in (150 mm) base at least 6 in past the spikes (CMHA PAV-TEC-003). The calculator starts the extension at the base thickness; edges against walls get none.
- Bedding sand: concrete sand (ASTM C33), not masonry sand or stone dust, screeded to an uncompacted nominal 1 in (25 mm). Uneven bases must be fixed, not filled with extra sand.
- Joints between pavers 1/16–3/16 in (2–5 mm); cut pavers fill gaps wider than 3/8 in (10 mm).
- Pavers 2 3/8 in (60 mm) thick for pedestrian areas, driveways and limited vehicle use; at least 3 1/8 in (80 mm) for streets, laid in a herringbone pattern.
- Edge restraints of aluminium, steel, plastic or concrete, with at least 1 in (25 mm) of vertical face against the pavers.
Block thickness by traffic (IS 15658)
IS 15658:2006 Table 1 recommends a minimum block thickness and grade per traffic category: 50 mm, M-30 for non-traffic areas (gardens, domestic drives, paths and patios); 60 mm, M-35 for light traffic (pedestrian plazas, car parks, residential roads); 80 mm, M-40 for medium traffic (city streets); 100 mm, M-50 for heavy traffic (bus terminals, industrial areas); 120 mm, M-55 for very heavy traffic (ports, container terminals). The standard has been revised as IS 15658:2021, so check the current table with your supplier or engineer.
Weights and the compaction allowance
Aggregate is delivered loose and shrinks when it is compacted. IS 875 (Part 1) Table 1 lists gravel at 1,600 kg/m³ loose and 1,920–2,160 kg/m³ rammed, so a rammed layer holds 20–35% more material than its loose volume suggests; the calculator starts at 20% and 1,600 kg/m³, and dry clean sand at 1,600 kg/m³ (1,540–1,600 in IS 875). Your supplier's figures for their material are better than either.
Limitations
- The cutting allowances for each pattern are starting points, not a standard: small, curved or many-cornered areas need more.
- Joint sand assumes joints filled to the full paver depth; polymeric sands have their own coverage tables by joint width and paver thickness — use the manufacturer's figure if it differs.
- Typed areas only add edging if you give their perimeter; L-shapes, rectangles, circles and triangles work it out.
- The base thickness is general guidance for well-drained soils. Driveways on clay, frost-prone sites and anything carrying trucks need a design for the soil and loads.
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Frequently asked questions
How many pavers are in a square metre?
Divide 1 m² by the paver size including one joint: 200 × 100 mm pavers with 3 mm joints cover 0.203 × 0.103 m each, so 47.8 per m². In US units 4 × 8 in pavers with 1/8 in joints are 4.3 per ft².
How thick should the base be under pavers?
CMHA PAV-TEC-002 gives at least 4 in (100 mm) of compacted aggregate base for patios and walks and 6 in (150 mm) for residential driveways on well-drained soils — more on wet or weak soils and in cold climates.
How much bedding sand do I need?
A nominal 1 in (25 mm) layer: 0.025 m³ per m², about 40 kg per m² at 1,600 kg/m³. 100 ft² at 1 in is 8.3 ft³, about 0.31 yd³.
How much extra should I buy for a herringbone pattern?
Herringbone at 45° has cuts along every edge, so the calculator starts at 15%; 90° herringbone and fans start at 10% and straight patterns at 5%. These are rules of thumb — raise them for small or irregular areas.
Do I need edging along the house wall?
No: an edge that is already held by a wall or an existing kerb needs no edge restraint. Enter the length of such edges and the calculator leaves it out.
How thick should interlocking blocks be?
For patios, paths and home driveways 60 mm (2 3/8 in) is usual (CMHA); IS 15658 Table 1 allows 50 mm where there is no traffic and asks for 80 mm and more for streets and heavier traffic.