Polymeric Sand Calculator
Work out how many bags of polymeric sand you need to fill paver joints. Enter the area, the paver size, the joint width and the fill depth; the calculator works out the actual joint volume, so it adapts to small bricks, large slabs and wide joints.
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For a mix of sizes, use the average size or the most common one.
Fill to about 1/8 in below the paver top. 2 3/8 in pavers → about 2 1/4 in.
Fill to about 3 mm below the paver top. 60 mm pavers → about 55–57 mm.
About 100 lb/ft³ (1,600 kg/m³) for most polymeric sands: a 50 lb bag fills ~0.5 cu ft.
How to use the Polymeric Sand Calculator
- Enter the paver area as length × width or a known square footage.
- Pick the paver size; for mixed patterns use the average or most common size.
- Choose the joint width and the depth you will fill (about 1/8 in below the paver top).
- Check the bag size and density; most 50 lb bags fill about half a cubic foot.
- Read the bags needed and compare other joint widths in the table.
The joint volume formula
For pavers of length L and width W with joints of width j, each paver plus half of its surrounding joints takes up a module of (L + j) × (W + j). The share of the surface that is joint is:
Joint share = 1 − (L × W) ÷ ((L + j) × (W + j))
Sand volume (cu ft) = area (sq ft) × joint share × depth (in) ÷ 12. Weight = volume × about 100 lb/ft³. Bags = weight ÷ bag size, rounded up.
Example: 240 sq ft of 6 × 9 in pavers with 1/8 in joints filled 2¼ in deep. Joint share = 1 − 54 ÷ (9.125 × 6.125) = 3.38%. Volume = 240 × 0.0338 × 2.25 ÷ 12 = 1.52 cu ft, plus 10% = 1.67 cu ft ≈ 167 lb, so 4 bags of 50 lb.
Approximate coverage per 50 lb bag
Patio area filled by one 50 lb bag at about 100 lb/ft³ and joints filled 2¼ in deep, before any extra allowance.
| Paver size | 1/8 in joints | 1/4 in joints | 1/2 in joints |
|---|---|---|---|
| 4 × 8 in | ~59 sq ft | ~31 sq ft | ~16 sq ft |
| 6 × 9 in | ~79 sq ft | ~40 sq ft | ~21 sq ft |
| 12 × 12 in | ~130 sq ft | ~66 sq ft | ~34 sq ft |
| 24 × 24 in | ~258 sq ft | ~130 sq ft | ~66 sq ft |
Tips for installing polymeric sand
- Work on a dry day with dry pavers and no rain expected for the curing time printed on the bag.
- Compact as you fill. Sweep sand in, run a plate compactor (with a pad) or tap the pavers, and top up until the joints stay full.
- Blow the surface clean with a leaf blower before wetting, so no binder is left on the paver faces to cause haze.
- Mist, do not flood. Follow the label's wetting steps; too much water washes the binder out of the joint.
- Buy one batch of the same color so the joints match, and keep a spare bag for future repairs.
Frequently asked questions
How do I calculate how much polymeric sand I need?
Find the share of the surface that is joints: 1 − (L × W) ÷ ((L + j) × (W + j)) for a paver L × W with joint width j. Multiply by the area and the joint depth in feet to get cubic feet, then by about 100 lb per cubic foot for the weight, and divide by the bag size. Add about 10% for sweeping and touch-ups.
How many square feet does a 50 lb bag of polymeric sand cover?
It depends on paver size and joint width. With 6 × 9 in pavers, 1/8 in joints and 2¼ in deep joints, a 50 lb bag covers roughly 80 sq ft. Small 4 × 8 in bricks have more joints, so a bag covers about 60 sq ft, while 24 × 24 in slabs with 1/8 in joints can reach about 260 sq ft. Wider joints cut coverage sharply.
How deep should polymeric sand be in paver joints?
Fill the joints to about 1/8 in below the top of the paver, or just below the chamfered edge, so water can run off and the sand is not scuffed. For standard 2⅜ in (60 mm) pavers that is about 2¼ in deep. Many products also specify a minimum depth, often around 1–1½ in.
How wide can joints be for polymeric sand?
Standard polymeric sands are typically made for joints from about 1/8 in up to 1 in. Wide-joint products are made for natural stone and joints of several inches. Check the label, because using the wrong product in wide joints can lead to cracking or washout.
Why do I need more bags than the label says?
Labels quote coverage for a particular paver and joint, often small bricks with narrow joints, and assume joints already partly filled. Large gaps, deeper joints, chipped edges and sand lost while sweeping all add up, which is why a 10% extra allowance is sensible.
Can I use regular sand instead of polymeric sand?
Yes, plain jointing sand works and is cheaper, but it washes out and lets weeds and ants in more easily. Polymeric sand contains binders that harden after wetting, locking the joints. It must be installed in dry conditions and kept off the paver surface to avoid haze.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.