Your Result Explained: Exact Takeoff Breakdown
An 18-foot round above-ground pool holds roughly 7,600 gallons of water—exerting over 63,000 lbs of downward pressure on the vinyl liner. To protect that liner from tiny pebbles, nutgrass, and root dimples, pool installers spread a smooth 2-inch cushion of fine screened masonry sand across the 254.47-square-foot circular footprint. Including a 10% allowance for water-tamping compaction and shaping the interior perimeter cove, you need 46.65 cubic feet (1.73 cubic yards) of fine sand, which weighs 2.25 US short tons (4,492 lbs).
Using the circle area formula (π × 9² = 254.47 sq ft) at a 2-inch depth yields a net geometric volume of 42.41 cubic feet (1.57 cubic yards or 2.04 tons). Adding 10% (4.24 extra cubic feet) is critical for above-ground pools because wetting and tamping the sand pad compresses it by ~8%–10%, and you also need extra sand to bank a 4-to-6-inch triangular cove around the inside bottom wall track if you are not using pre-formed foam cove strips. In retail packaging, 46.65 cubic feet equals 94 standard 50-lb bags.
Ordering 2.25 to 2.5 tons of bulk washed masonry sand from a local landscape yard costs around $101 to $125 for the sand plus $75–$100 for dump truck delivery ($175–$225 total). Buying 94 retail 50-lb bags at $5.75 per bag would cost roughly $540 and require cutting open and dumping nearly 100 heavy plastic bags.
Step-by-Step Math: 18-Foot Round Pool Pad at 2" Depth
Calculating bulk masonry sand (2,600 lbs/yd³) and 50-lb bags for an 18-foot diameter circular pool base at 2 inches deep with 10% tamping/cove allowance.
- Radius from Diameter: 18 ft ÷ 2 = 9.00 ft radius.
- Circular Surface Area: π × 9² = 3.1416 × 81 = 254.47 sq ft (23.64 sq m).
- Net Cubic Feet at 2" Depth: 254.47 sq ft × (2 in ÷ 12) = 42.41 cu ft (1.57 cu yd net).
- Gross Cubic Feet (with 10% allowance): 42.41 cu ft × 1.10 = 46.65 cu ft.
- Gross Cubic Yards: 46.65 cu ft ÷ 27 = 1.73 cubic yards (1.32 cu m).
- Total Weight in Pounds: 1.728 yd³ × 2,600 lbs/yd³ = 4,492 lbs (2,038 kg).
- Total Weight in US Short Tons: 4,492 lbs ÷ 2,000 = 2.25 tons (range: 2.07 to 2.33 tons).
- 50-lb Retail Bag Count (0.5 cu ft/bag): ceil(46.65 ÷ 0.5) = 94 bags.
Bottom Line: Order 2.25 to 2.5 tons (or 1.75 to 2.0 cubic yards) of fine screened masonry sand in bulk.
How This Scenario Is Calculated
For a circular pool pad, we divide the 18-foot diameter by 2 to get a 9-foot radius, square it (81), and multiply by pi (3.14159) to obtain 254.47 square feet. Multiplying 254.47 sq ft by 2/12 ft (0.1667 ft) gives 42.41 net cubic feet. Adding 10% for tamping and cove work yields 46.65 cubic feet, or 1.73 cubic yards.
Applying the ASTM C144 bulk density for fine screened masonry sand (2,600 lbs/yd³ or 1.30 tons/yd³), 1.728 cubic yards weighs 4,492 lbs, or 2.25 US short tons. Dividing 46.65 cubic feet by 0.5 cubic feet per 50-lb bag rounds up to 94 bags.
Cubic Yards = [ Area (sq ft) × (Depth (in) ÷ 12) × (1 + Waste%) ] ÷ 27 Tons = [ Cubic Yards × Sand Density (lbs/yd³) ] ÷ 2,000 Bags (50-lb) = Ceiling( Gross Cubic Feet ÷ 0.5 ) Project-Specific Tips & Common Mistakes
Never Use Sand to Level a Sloped Yard
Sand is strictly a 2-inch protective liner cushion—it has zero structural strength on a slope and will wash out under 63,000 lbs of water. Always excavate the high side of your yard down to level virgin soil before setting the pool ring and spreading sand.
Ask Specifically for "Double-Screened Masonry Sand"
When calling a landscape supply yard, specify fine ASTM C144 masonry sand (also called plaster sand or mortar sand) with zero pebbles. Do not accept coarse concrete sand or unscreened fill sand, which contain sharp stones that can puncture vinyl liners under water pressure.
Dump the Sand Inside the Cleared Circle Before Installing the Wall
Once the steel pool wall is uncoiled into the bottom track, lifting 4,492 lbs of sand over a 48-inch or 52-inch sheet-metal wall without buckling it is exhausting and risky. Wheel the 1.73 cubic yards of sand into a pile at the exact center of the cleared circle before raising the pool wall.
Mistake Forgetting to treat the bare dirt for nutgrass before dumping sand
Recommended Fix: Nutgrass (nutsedge) shoots can pierce right through 2 inches of sand and a 20-mil vinyl pool liner. Apply a pre-emergent turf herbicide or lay a commercial non-woven pool gorilla pad over the tamped sand before dropping the liner.
Mistake Leaving footprints in the damp sand when hanging the liner
Recommended Fix: Every heel mark in the sand pad becomes a permanent crater on the pool floor that traps dirt and vacuum heads. Mist and tamp the sand flat with a lawn roller, then wear flat foam kneeling boards on your feet while smoothing the final surface.
Reference Coverage Table (Dry Play Sand / Fine Masonry Sand (ASTM C144))
Compare how coverage changes across common depths for Dry Play Sand / Fine Masonry Sand (ASTM C144) (default planning density 2600 lbs/yd³):
| Depth | 1 Cubic Yard Covers | 1 Ton Covers | Yards / 100 sq ft | Tons / 100 sq ft | Bags (0.5 ft³) / 100 sq ft |
|---|---|---|---|---|---|
| 0.5 in | 648 sq ft | 498.5 sq ft | 0.15 yd³ | 0.2 tons | 9 bags |
| 1 in | 324 sq ft | 249.2 sq ft | 0.31 yd³ | 0.4 tons | 17 bags |
| 2 in Active | 162 sq ft | 124.6 sq ft | 0.62 yd³ | 0.81 tons | 34 bags |
| 4 in | 81 sq ft | 62.3 sq ft | 1.23 yd³ | 1.6 tons | 67 bags |
| 6 in | 54 sq ft | 41.5 sq ft | 1.85 yd³ | 2.41 tons | 100 bags |
| 8 in | 40.5 sq ft | 31.2 sq ft | 2.47 yd³ | 3.21 tons | 134 bags |
Reference Source: ASTM C144 masonry aggregate standard & Quikrete Play Sand yield data (50 lb bag ≈ 0.5 ft³).
Frequently Asked Questions
Should I measure 18 feet or 19–20 feet for an 18-foot round pool?
While the sand cushion itself sits inside the 18-foot bottom rail, you should excavate and level the ground to 19 or 20 feet in diameter so the patio blocks under the vertical uprights sit flat. If you also spread a 2-inch sand bed across a full 20-foot circle (314.16 sq ft) with 10% waste, volume increases from 1.73 cubic yards (2.25 tons) to 2.13 cubic yards (2.77 tons).
How much extra sand do I need for the pool cove if I do not use foam cove strips?
An 18-foot round pool has a circumference of 56.5 feet (π × 18). Building a traditional 6" × 6" triangular sand cove around that 56.5-foot interior wall takes about 7.1 cubic feet (0.26 cubic yards or 0.34 tons) of sand. Combined with the 2-inch floor pad, ordering 2.5 tons (2 cubic yards) covers both the floor and a hand-formed sand cove.
How much sand do Other Common Round Pool Sizes (15 ft, 21 ft, 24 ft) Need at 2" Deep?
With a 10% allowance at 2 inches deep: a 15-ft round pool (176.7 sq ft) needs 1.20 cubic yards (1.56 tons or 65 bags); a 21-ft round pool (346.4 sq ft) needs 2.35 cubic yards (3.06 tons or 127 bags); and a 24-ft round pool (452.4 sq ft) needs 3.07 cubic yards (3.99 tons or 166 bags).
Can I use stone dust (screenings) instead of masonry sand under an above-ground pool?
Limestone screenings or decomposed granite fines pack harder than masonry sand, which reduces heel divots, but they must be finely screened and topped with a geotextile pool pad so no sharp rock splinters touch the vinyl liner.
Is 2 inches of sand enough for an Intex soft-sided frame pool?
Yes, a 1.5-to-2-inch layer of wetted, tamped masonry sand topped with a woven tarp or commercial pool pad provides a smooth, comfortable floor for 18-foot Intex Ultra XTR or Prism frame pools, provided the wooden or concrete blocks under every metal leg are recessed flush with the compacted dirt.