Polymeric Sand Calculator
This polymeric sand calculator divides paved area by 60 sq ft per 50-lb bag and rounds up: a 20 × 10 ft patio is 3.33, so 4 bags, or $100 at $25 a bag.
How much polymeric sand you need
A polymeric sand calculator tells you how many bags to buy for the joints of a paver surface. Enter the length and width of the paved area in feet. The tool divides the area by 60 square feet per 50 lb bag, rounds up, and multiplies by your price per bag.
Think of the joints as thin cracks between the pavers that you have to fill. Wider joints and thicker pavers swallow more sand. The 60 figure is an average for ordinary joints.
The formula in plain words
- Paved area = length × width.
- Bags = area ÷ 60.
- Round up to a whole bag.
- Cost = bags × price per bag.
Worked example: the default patio
A patio measures 20 ft by 10 ft. Bags cost $25.
- Area: 20 × 10 = 200 sq ft
- Bags: 200 ÷ 60 = 3.33
- Rounded up: 4 bags
- Cost: 4 × $25 = $100
You pay for 4 bags even though you need only 3.33, because the fourth bag has to be opened. The leftover is about two thirds of a bag, which is handy for topping off joints after the first rain settles them.
Worked example: a patio that comes out even
A patio measures 15 ft by 12 ft.
- Area: 15 × 12 = 180 sq ft
- Bags: 180 ÷ 60 = 3.00
- Cost: 3 × $25 = $75
There is no spare sand here. If your joints are wider than standard, you may run short, so check a few joints before you commit.
Bags needed by paved area
| Paved area | Bags |
|---|---|
| 100 sq ft | 2 |
| 150 sq ft | 3 |
| 200 sq ft | 4 |
| 300 sq ft | 5 |
| 500 sq ft | 9 |
The 500 sq ft row is 8.33 bags before rounding. At large sizes the extra bag is a smaller share of the total.
How to measure
Measure the length and width of the paved surface in feet. For an L-shape or a curved edge, split the area into rectangles and add them. Do not include any border that is not paved, such as a gravel edge restraint.
If you used large format pavers with tight joints, you need less sand. If you used small bricks, you have more joint length per square foot, and you need more.
Installing it right
Polymeric sand only performs if the joints are clean and the surface is dry when you start. Sweep the sand into the joints, compact the pavers lightly, then sweep again to fill the gaps that settle. Blow or broom every grain off the surface before you wet it, because any sand left on top will harden into a stain.
Follow the manufacturer’s instructions for watering and for the dry time afterward. Different products have different rules, and the label controls.
Why joints take more sand over time
Joints settle after the first sweep, so plan a second pass. The sand compacts as you run a plate compactor over the pavers, and again when you water it. Keep a partial bag on hand for that second fill. Opened bags should be closed and kept dry, because moisture will start the binder reacting inside the bag.
Common mistakes
- Skipping the round-up. Half a bag short means unfilled joints.
- Buying a different color for the last bag. Lot-to-lot variation shows on a finished patio.
- Applying it to wet or dirty joints. The binder will not cure correctly.
- Leaving residue on the paver surface. It can leave a haze that is hard to remove.
- Filling joints to the very top. Leave a small gap below the paver edge, as the label says.
- Using it where water pools. Poor drainage will wash it out over time.
Related calculators
Before sand goes in the joints, you need the pavers themselves. The paver calculator counts them, and the paver sand calculator estimates the bedding layer under them. For the base below that, use the gravel calculator.
Frequently asked questions
How many bags of polymeric sand do I need?
Divide the paved area by 60 and round up to a whole bag. A 20 ft by 10 ft patio is 200 sq ft, which is 3.33 bags, so you buy 4.
What does one 50 lb bag cover?
The calculator uses 60 sq ft per bag for standard joints. Real coverage depends on joint width, paver thickness, and how well you sweep, so read the coverage chart on the product you buy.
Why does the page round up?
Bags are sold whole. A shortfall in the middle of a job leaves some joints unfilled, and mixing batches from different lots can leave a color difference.
Is polymeric sand the same as paver base sand?
No. Base or bedding sand sits under the pavers. Polymeric sand is a fine sand with a binder that goes into the joints on top, and it hardens when wet. The paver sand calculator covers the bedding layer.
Can I install polymeric sand if rain is coming?
Follow the product label. Most brands need the surface and joints dry at install and a rain-free period afterward. Wetting it too soon can leave a haze on the pavers or wash the binder out.
Estimates only. Verify quantities with your supplier before purchasing.