Polymeric Sand Calculator
Joint sand is measured by the volume of the gaps, not the patio. Tell us the paver and the joint and get a bag count you can trust.
Why joint width changes everything
joint share = 1 − W × L ÷ (W + j)(L + j) · lb = area × share × depth ÷ 12 × 90 lb/ft³
The sand only fills the gaps. For a 4×8 paver with a 1/8-inch joint, the joints are about 4.5% of the surface; widen them to 1/2 inch and they become 16% — three and a half times the sand for the same patio. That is why a single “sq ft per bag” figure on a label is only a starting point. Dry polymeric sand weighs roughly 90–100 lb per cubic foot.
Installing polymeric sand
- Start with a completely dry surface and dry joints.
- Sweep the sand into the joints, then run a plate compactor (with a pad) over the pavers to settle it. Repeat until full to ⅛ in below the top.
- Blow every grain off the paver faces with a leaf blower — leftover haze bonds and stains.
- Mist with water in stages as the bag directs; don’t flood it.
Questions people ask
How much area does a 50-lb bag of polymeric sand cover?
It depends on the joint. With 4×8 pavers, 1/8-inch joints and 2⅜-inch-thick pavers, a 50-lb bag fills roughly 55–75 sq ft. Wide joints on tumbled or natural stone can drop that to 15–30 sq ft per bag. Big-format slabs with narrow joints stretch it past 100 sq ft.
How deep should polymeric sand go in the joints?
Fill the full depth of the joint to about 1/8 inch below the paver’s top edge (or below the chamfer). Manufacturers such as Techniseal and Alliance Gator recommend filling at least 1½ inches deep so the binder can cure into a solid joint.
What joint width can polymeric sand handle?
Standard polymeric sands work on joints from about 1/8 inch to 1 inch wide. For wider flagstone joints of up to 4 inches, use a product made for wide joints; ordinary polymeric sand will crack if spread too wide.
Why do tumbled pavers need more joint sand?
The rounded, chipped edges on tumbled pavers form a V at the top of each joint, which holds more sand than a straight joint of the same width. Add 20–30% or set the joint width a little wider in the calculator.