Polymeric sand is joint sand mixed with a binder that hardens when wetted, locking pavers together and resisting weeds and ants. Bag labels give wide coverage ranges because the amount depends on the joints: small pavers have far more joint length per square foot than large slabs, and wider or deeper joints hold more sand. This polymeric sand calculator measures the joint volume from your paver size, joint width and fill depth, converts it to pounds and bags, and shows the coverage per bag for your layout. A 12 × 12 ft patio of 4 × 8 inch pavers with 3/16 inch joints, filled 2.25 inches deep, needs about 210 lb, or 5 bags.
Counting pavers and base too? Start with the paver calculator. For irregular stone, see the flagstone calculator.
How to use the polymeric sand calculator
- Enter the patio length and width.
- Enter the paver length and width. For mixed-size patterns, use a size near the average, or run each size separately.
- Enter the joint width. Concrete pavers with spacer nibs usually have joints of about 1/8 to 3/16 inch; natural stone and tumbled pavers are often wider.
- Enter the fill depth. For new paving, fill to about 1/8 inch below the top of the paver (for 2-3/8 inch pavers, about 2.25 inches). Polymeric sand makers generally require a minimum depth, often around 1 to 1.5 inches, for the binder to hold.
- Keep about 10% extra for sweeping and spillage, then pick the bag size.
Formula
We assume dry polymeric sand weighs about 100 lb per cubic foot once it is swept and compacted into the joints; check your product if it lists a different bulk density.
Worked example
A 12 × 12 ft patio of 4 × 8 inch pavers, 3/16 inch joints, filled 2.25 inches deep, with 10% extra.
- Joint volume: 144 × (8 + 4) ÷ 32 × 0.1875 × 2.25 = 144 × 0.375 × 0.4219 = 22.8 in³ per ft².
- Weight: 22.8 ÷ 1,728 × 100 = 1.32 lb per ft².
- Total: 144 × 1.32 × 1.10 = 209 lb, so 5 bags of 50 lb (4.2 bags exactly).
- Coverage: one 50 lb bag fills about 38 ft² of this layout.
The same patio laid with 12 × 12 inch slabs would need less than half as much sand (about 93 lb).
Polymeric sand coverage per 50 lb bag
Square feet filled by one 50 lb bag at a 2.25 inch fill depth (new 2-3/8 inch pavers), no waste. Halve the depth and the coverage doubles.
| Paver size | 1/8 in joints | 3/16 in joints | 1/4 in joints | 3/8 in joints |
|---|---|---|---|---|
| 4 × 8 in | 57 ft² | 38 ft² | 28 ft² | 19 ft² |
| 6 × 6 in | 64 ft² | 43 ft² | 32 ft² | 21 ft² |
| 6 × 9 in | 77 ft² | 51 ft² | 38 ft² | 26 ft² |
| 12 × 12 in | 128 ft² | 85 ft² | 64 ft² | 43 ft² |
| 16 × 16 in | 171 ft² | 114 ft² | 85 ft² | 57 ft² |
| 24 × 24 in | 256 ft² | 171 ft² | 128 ft² | 85 ft² |
Installing polymeric sand
Polymeric sand only works when it fills the joint and is activated correctly. The pavers must be completely dry, the sand swept and compacted into the joints (a plate compactor with a pad helps it settle), and every grain of residue blown off the surface before misting with water, or it can leave a haze. Follow the product's watering instructions and weather window. On a new patio, the bedding sand under the pavers is regular concrete sand; size that with the sand calculator. The Interlocking Concrete Pavement Institute publishes installation guidance for joint sand. For raised patios, the retaining wall block calculator handles the wall.
Caveats and assumptions
- Joint widths vary across a patio; measure several and use an average.
- Tumbled pavers and pavers with chamfered edges hold more sand than square-edged pavers of the same size.
- Product densities differ. If your label lists coverage for your paver size, compare it with the result here.
- Some polymeric sands are rated for narrow joints only, others for wide stone joints. Choose a product rated for your joint width.
Frequently asked questions
How much polymeric sand do I need?
Work out the joint volume from paver size, joint width and depth. For 4 × 8 pavers with 3/16 inch joints filled 2.25 inches deep, it is about 1.3 lb per ft², so a 50 lb bag covers about 38 ft².
How many square feet does a 50 lb bag of polymeric sand cover?
At a 2.25 inch fill depth, from about 20 ft² for 4 × 8 pavers with 3/8 inch joints to about 250 ft² for 24 × 24 slabs with 1/8 inch joints. Shallower fills cover proportionally more.
How deep should polymeric sand be in paver joints?
Fill the full joint to about 1/8 inch below the paver surface. Manufacturers typically require a minimum depth, often around 1 to 1.5 inches, for the binder to hold.
How much polymeric sand for a 10x10 patio?
For 4 × 8 pavers with 3/16 inch joints filled 2.25 inches deep, about 145 lb with 10% extra, so 3 bags of 50 lb.
Can I use polymeric sand on flagstone?
Yes, if you choose a product rated for wide joints, typically sold for natural stone. Joints that are too wide or shallow for the product can crack or wash out.
Sources
- Interlocking Concrete Pavement Institute — joint sand and segmental paver installation guidance
- Techniseal — polymeric sand products — joint width, depth and activation instructions
- Alliance Gator — polymeric sand products — joint ranges and coverage by paver type
This calculator gives estimates for planning and education. Check measurements, local codes, supplier specs and your school's official policy before relying on a result. See our disclaimer and how we build and check calculators.