Polymeric Sand Calculator

The calculator divides your paved area by the coverage of one 50 lb bag, then rounds up to whole bags. Joint width matters most: narrow joints between tight-fitting pavers take far less sand than the wide, uneven gaps around natural stone. The table uses narrow joints (about 70 sq ft per bag).

Those counts cover the joints only. The 1 inch bedding layer under the pavers is regular washed concrete sand, not polymeric sand; work that out with the paver sand calculator.

Manufacturers publish coverage as a range because joint depth, paver thickness and how much the surface has been tamped all change how much sand settles in. PourCanvas uses one value inside each published range:

• Narrow joints (joints 1/8–3/8 in: 65–85 sq ft per bag (gator)): the calculator uses 70 sq ft per 50 lb bag; published coverage is undefined.
• Wide joints (joints 3/4–1 1/4 in: 22–42 sq ft per bag (gator)): the calculator uses 33 sq ft per 50 lb bag; published coverage is undefined.

Small square pavers have more joint length per square foot than large slabs, so a patio of 4×8 inch bricks lands at the low end of the coverage range. Large porcelain or travertine slabs land at the high end. Check the bag label for your brand, then adjust if needed.

Pavers with wide or open joints, such as tumbled stones, cobbles and spaced slabs, need a wide-joint polymeric sand, and a lot more of it. On the same 12×16 patio, the count goes from 3 bags for narrow joints to 6 bags for wide joints.

Narrow-joint products are not made to bridge wide gaps and can crack or wash out. Buy the product rated for your joint width.

Dry-laid flagstone has irregular joints that are often wide, so the calculator always uses wide-joint coverage when you choose flagstone. A 12×16 flagstone patio needs about 6 bags; a 4×30 flagstone path needs 4.

To order the stone itself, use the flagstone calculator. Our flagstone guide explains dry-laid and mortared setting methods.

Polymeric sand costs about $30–80 per 50 lb bag, depending on brand and whether it is a standard, wide-joint or premium product. Multiply that by your bag count:

• 10×10 patio: 2 bags, about $60–160
• 4×30 walkway: 2 bags, about $60–160
• 12×16 patio: 3 bags, about $90–240
• 12×16 patio, wide joints: 6 bags, about $180–480
• 20×20 patio: 6 bags, about $180–480

Joint sand is a small share of a paver budget. The paver patio cost calculator shows the full installed price, and the paver calculator lists every material.

Regular joint sand is plain fine sand swept into the joints. It is cheap and easy to top up, but it washes out, lets weeds root and gives ants an easy home. Polymeric sand is fine sand blended with a binder that hardens once wetted. The cured joint stays flexible enough for the pavers to move slightly, yet it resists washout, weeds and insects.

• Choose polymeric sand for patios, walkways and driveways where you want low-maintenance joints.
• Choose regular sand for a quick temporary fix, or where you want joints that are easy to top up by hand.
• Use neither on permeable pavers: their open joints are filled with small chip stone so water can drain through.

For the trade-offs of the pavers themselves, see our concrete patio vs pavers comparison.

• Start dry. The pavers, the joints and the bedding sand below must be fully dry. Moisture activates the binder early and leaves a haze.
• Spread and sweep. Pour the sand onto the surface and sweep it diagonally across the joints until they are full.
• Compact. Run a plate compactor with a protective pad over the pavers to settle the sand, then sweep in more and repeat until the joints stay full to just below the paver chamfer.
• Clean the surface. Sweep, then use a leaf blower to clear every grain off the paver faces.
• Mist. Wet the joints with a gentle shower setting in small sections. Follow the bag's directions on how many passes to make; flooding the joints washes the binder out.

A full install sequence, including base and bedding, is in our concrete walkway design guide.

Polymeric sand needs dry weather on both sides of the install. Rain before application leaves damp joints that won't fill properly; rain soon after misting can wash the binder out before it sets. Every brand states a minimum rain-free period and a temperature range on the bag, so plan the job around that, not around a general rule.

• Pick a day with a dry forecast and no overnight rain expected.
• Avoid very hot, sunny afternoons, when the mist evaporates before it soaks in.
• Avoid cold days near freezing, when the binder cures slowly or not at all.
• Keep foot traffic and furniture off until the bag's cure time has passed.

Well-installed polymeric joints last for years, but they don't last forever. Plan to re-sand when you see joints sitting well below the paver edge, sand washing onto the surface after rain, weeds or ants coming through, or pavers starting to shift. Remove the old joint material to a depth of about an inch, clean the surface, let it dry and repeat the install steps above. A patio with mostly sound joints only needs the bad areas redone, so one or two bags usually covers a touch-up. For a complete rebuild or a new area, start from the paver base calculator and work up layer by layer.