Polymeric Sand Calculator

Polymeric sand fills the joints between pavers. When wet, the polymers bind into a flexible mortar that locks pavers in place, blocks weeds, and shrugs off ant tunneling. Get the quantity wrong and either you waste expensive sand or you stop halfway through and the joints harden unevenly.

Coverage depends heavily on joint width and paver size. Manufacturers (TechniSeal, SuperSand, EnviroSEAL) publish coverage tables that all roughly agree:

• Standard pavers (4 x 8 in), 1/8 inch joints: 75 to 100 sq ft per 50 lb bag
• Standard pavers, 1/4 inch joints: 50 to 75 sq ft per bag
• Large format (12 x 24 in), 1/4 inch joints: 80 to 100 sq ft per bag
• Wide joints (1/2 inch+, flagstone): 25 to 40 sq ft per bag
• Narrow joints (1/16 inch, cobbles): 100 to 130 sq ft per bag

Why the coverage rate swings so much: what you are really filling is the total joint volume, which is the running length of joint per square foot multiplied by the joint width and the joint depth. Small pavers pack far more joint into the same area than large slabs do, and a quarter-inch joint holds four times the sand of a sixteenth-inch one at the same depth. That is the whole story behind the table above, and it is why picking the row that matches your paver beats any general rule.

So skip the volume arithmetic and work from the table:

bags = ceil(area_sqft / coverage_per_bag x 1.10)

The 10% buffer is not optional. Polymeric sand activates when wet, and a bag opened and left more than an hour starts to clump. Run short mid-job and you cannot simply drive to the store and finish two hours later, because the first sweep has already locked in and the new sand will not bond to it.

Activation rules:

• Sweep into joints when pavers are bone dry. Compact with a plate compactor.
• Sweep again, top the joints back up, then shower-spray to activate. A heavy hose stream washes the sand straight out.
• Keep rain off it for 24 hours.
• Joints need at least 1.5 inches of depth to lock properly. Fill to roughly 1/8 inch below the paver surface, and never let the sand sit proud of the top. A joint left far below the surface ponds water and washes out.

Bags come in 50 lb (most common) or 35 lb (lighter, easier to lift). Prices run somewhere around $25 to $45 per 50 lb bag, though that moves with region and year, so check locally. Cheaper grades tend to crumble within two seasons.