YepCalc

Polymeric Sand Calculator

Find how much polymeric sand you need to fill the joints between pavers, by weight and in bags. Enter the area, the paver size and thickness, and the joint width. It works the same way for kiln-dried jointing sand.

Section 1

Add more areas, or subtract areas that need no joint sand, such as a planter.

Paver and joint size

Use the actual size of the paver, which can be slightly smaller than the nominal size.

Use the thickness on the spec sheet. Patio and driveway pavers are often 2 3/8 in (60 mm) thick.

For concrete pavers, joints are usually 1/16 to 3/16 in (2 to 5 mm).

Leave blank to fill the joints to the full paver thickness.

Sand density

Typical joint sand: 112.4 lb/ft³

Waste, bags, and cost

%

Recommended for joint sand: 10%

For a bag or pail not listed, enter the weight printed on it.

per

Result

Enter the dimensions of an area to see the joint sand you need.

How much joint sand you need

This calculator is for the sand you sweep into the joints after the pavers are laid. For the bedding sand under the pavers and the base, use the Paver Calculator.

Joint sand fills the gaps between pavers, so the amount depends on the joint width and depth and on how many joints there are per square foot. Each paver shares the joints around it with its neighbors, so one paver and its share of the joints cover (paver length + joint) × (paver width + joint). The calculator finds the joint sand per unit of area as:

Sand per area = joint width × (paver length + paver width + joint width) × joint depth ÷ ((paver length + joint width) × (paver width + joint width))

Sand volume = net area × sand per area × (1 + waste % ÷ 100)

Sand weight = sand volume × density

Bags = sand weight ÷ weight per bag, rounded up

Convert every measurement to the same unit before you multiply. The joint depth is the paver thickness unless you enter a smaller depth. With several sections, the calculator adds the sections set to Add and subtracts those set to Subtract. For shapes other than rectangles, it uses these formulas:

Shape Area
Rectangle length × width
Circle π × diameter² ÷ 4 (or π × radius²)
Triangle (base and height) base × height ÷ 2
Triangle (three sides) Heron's formula: √(s(s − a)(s − b)(s − c)), where s = (a + b + c) ÷ 2
Trapezoid (parallel side A + parallel side B) ÷ 2 × height
Ring π × (outer diameter² − inner diameter²) ÷ 4
Rectangular border outer length × outer width − (outer length − 2 × border width) × (outer width − 2 × border width)
Known area the area you enter

The calculator counts the pavers in straight rows with even joints. Cut pavers along the edges are covered by the waste allowance. For a pattern that mixes several paver sizes, such as a 3-piece system, enter the average length and width of the pavers in the pattern. The result is then an estimate.

Polymeric sand is fine sand mixed with a binder that hardens when you wet it. Kiln-dried sand is plain dry fine sand, common for block paving in the UK. Both fill the same joints, so the calculator uses the same formula and density for both.

Paver thickness, joint depth, and joint width

Paver thickness and joint depth

The amount of sand grows with the joint depth, so enter the thickness on the paver's spec sheet. The Concrete Masonry and Hardscapes Association (CMHA) calls for pavers 2 3/8 in (60 mm) thick for pedestrian areas and driveways, and at least 3 1/8 in (80 mm) for streets and industrial paving. UK block paving is often 50 to 80 mm thick.

Leave Joint depth blank to fill the joints to the full paver thickness. That's how manufacturers' calculators and coverage charts work, so you can compare the results. In practice, makers of polymeric sand ask you to stop the sand about 1/8 in (3 mm) below the top of the pavers, or below the chamfer on beveled pavers. To get that amount, enter the paver thickness minus 1/8 in, or minus the chamfer. For 2 3/8 in pavers, a 2 1/4 in depth needs about 5% less sand than leaving the field blank.

Polymeric sands also need a minimum joint depth, such as 1 1/2 in (38 to 40 mm) for some products. For thin pavers, check the label of the product you plan to use.

Joint width

Joint sand depends strongly on the joint width. With 4 × 8 × 2 3/8 in pavers, 3/16 in joints take about 47% more sand than 1/8 in joints. CMHA gives 1/16 to 3/16 in (2 to 5 mm) as the usual range for concrete pavers, and some polymeric sands need joints of at least 1/8 in. Measure the joints between your pavers and enter what you find.

Most concrete pavers have spacer bars on their sides. The calculator treats each joint as an even gap and doesn't take the spacer bars out, so for pavers with large spacer bars it gives a little more sand than you need. Tumbled pavers, with rounded and chipped edges, have wider and uneven joints. Enter the average width at the top of the joints, and raise the waste allowance.

Joint sand density

Joint sand is sold by weight, so turning the volume of the joints into pounds or kilograms needs a density. The calculator uses 112.4 lb/ft³, 1,800 kg/m³, 1.8 t/m³. That's the weight of dry sand it takes to fill a cubic foot or cubic meter of joints, after the sand is swept in, compacted, and topped up.

The value comes from the sand calculators that two polymeric sand makers, Techniseal and Alliance Gator, publish for their products. It sits at the high end of their common colors, so with the waste allowance the result is at least what their calculators give for those colors. Products differ, though: their figures range from about 89 to 127 lb/ft³. A bag of some products covers up to about 26% more area than this calculator shows, and a bag of the heaviest, such as dark or black sands, about 11% less.

Check the coverage chart on the bag you buy. If it shows a smaller area per bag than the table below, raise the waste allowance or enter the product's density.

The same density works for kiln-dried sand. For 200 × 100 mm blocks with 3 mm joints, UK suppliers' coverage figures for a 25 kg bag are close to or larger than the calculator's, so the calculator errs on the side of more sand.

The Sand Calculator uses a lighter density, for loose sand spread in a layer. Joint sand is packed into the joints, so it weighs more per cubic foot. Weigh and use the sand dry: manufacturers ask for dry sand and dry joints.

How much area a bag of joint sand covers

These areas come from the calculator's own formula, a density of 112.4 lb/ft³ (1.8 t/m³), no waste allowance, and joints filled to the full paver thickness. Pavers are listed as length × width × thickness. The areas are not copied from manufacturers' charts, and your product's chart may differ.

Area covered by a 50 lb bag

Paver and joint Area
4 × 8 × 2 3/8 in, 1/16 in joints 97.7 ft²
4 × 8 × 2 3/8 in, 1/8 in joints 49.7 ft²
4 × 8 × 2 3/8 in, 3/16 in joints 33.7 ft²
6 × 6 × 2 3/8 in, 1/8 in joints 55.6 ft²
6 × 9 × 2 3/8 in, 1/8 in joints 66.5 ft²
4 × 8 × 3 1/8 in, 1/8 in joints 37.8 ft²

Area covered by a 25 kg bag

Paver and joint Area
200 × 100 × 50 mm, 3 mm joints 6.4 m²
200 × 100 × 60 mm, 2 mm joints 7.9 m²
200 × 100 × 60 mm, 3 mm joints 5.3 m²
200 × 100 × 60 mm, 5 mm joints 3.3 m²
200 × 100 × 80 mm, 3 mm joints 4.0 m²

To include waste, divide the area by 1 plus the waste allowance. With 10%, a bag covers the area in the table ÷ 1.1.

How much extra joint sand to buy

The calculator adds 10%, as Techniseal's sand calculator does. You sweep the sand into the joints, compact the pavers, fill the joints again, and sweep the extra off the surface, so some sand is always left over or swept away. Raise the waste allowance for tumbled or chipped pavers and for areas with many cuts.

Running short means buying another bag later, and natural sand can vary in color from batch to batch. Buying enough at once avoids that.

Joint sand bag sizes

Joint sand is sold in bags and pails labeled by weight, in the US as well as in metric countries, so the calculator counts bags by weight. The 40 lb size is often a pail; count it the same way. The 22.7 kg size is the 50 lb bag sold in Canada. The calculator shows these sizes:

Bag Examples
50 lb Alliance Gator Gator Maxx G2, Sakrete Paver Set
40 lb Sakrete Paver Set and PermaSand (pail)
35 lb Techniseal EZSand
25 kg Holcim and Marshalls kiln-dried sand (UK), KING PermaSand (Canada)
22.7 kg Techniseal RG+ (Canada, labeled 50 lb)
20 kg Alliance Gator Europe, Mansfield Sand (UK)

For another size, such as a 27.5 lb (12.5 kg) pail, enter its weight in Custom bag size.

Examples

A paver patio

A patio 10 ft × 12 ft is 120 ft². With 4 × 8 × 2 3/8 in pavers and 1/8 in joints, one paver's joints take 1/8 × (4 + 8 + 1/8) = 1.516 in², and one paver with its joints covers 4.125 × 8.125 = 33.52 in². So each square foot needs 144 × 1.516 × 2.375 ÷ 33.52 = 15.47 in³ of sand. For 120 ft² that's 1,855.9 in³, or 2,041.5 in³ with 10% added: 1.18 ft³ (33.45 L). At 112.4 lb/ft³, you need 133 lb (60 kg): 3 bags of 50 lb, or 4 of 40 or 35 lb.

If you fill the joints to 2 1/4 in, 1/8 in below the top, you need 126 lb, still 3 bags of 50 lb. With 3/16 in joints instead of 1/8 in, the same patio needs 196 lb, or 4 bags.

Metric block paving

A drive 5 m × 4 m is 20 m². With 200 × 100 × 60 mm blocks and 3 mm joints, each square meter needs 3 × 303 × 60 ÷ (203 × 103) = 2.61 L of sand. For 20 m² that's 52.17 L, or 57.39 L with 10% added. At 1.8 t/m³, you need 103 kg, so 5 bags of 25 kg.

FAQ