Sand Calculator: Sizing Two Inches Under a Pool

Pool season here is decided by the ground, not the calendar. The lawn has to be dry enough to take a wheelbarrow without rutting, and the sand has to be dry enough to screed, which after a run of Maryland thunderstorms it will not be. This page follows one job from the first tape measure to the last pass of the screed board, with the sand calculator sitting in the middle of it, and the same sequence works for a play box, a leveling pass over a tired lawn or a mortar batch.

Reading the week before the sand is ordered

Wet sand does not change the number of cubic yards a job takes. It changes everything about handling it: a soaked pile is heavy on the shovel and it smears instead of leveling out. On the flat Coastal Plain ground of the Eastern Shore and Southern Maryland, where the water table sits close and the land sheds slowly, a low garden can stay unworkable for days after a storm. In the Piedmont the silt firms up faster, but it still turns soft while it is saturated.

So the order of operations is weather first. Pick a dry stretch, have the material arrive in the week you intend to use it rather than two weeks ahead, and keep a tarp over the pile from the moment it lands.

Marking out the ring, then adding the working margin

An above-ground pool sits on a level bed that runs wider than the pool itself, because you need somewhere to stand while you screed and somewhere for the rim to bed down. For an 18-foot pool, mark a 20-foot circle: the pool diameter plus a foot of margin all the way round.

Measure the diameter straight across the widest point rather than following the curve with the tape. Strip the turf inside the ring and take out anything stony, since the one thing a liner will not forgive is a sharp edge underneath it.

Turning the ring into a quantity

Choose the circle setting and enter 20 in the diameter box, in feet. Depth goes in as inches, and for a pool base that figure is 2. The box takes anything from 0.25 up to 24, so the same form handles a half-inch leveling pass and a six-inch play box without changing gear. Pick the material next, because the selection is what sets the weight the tool converts with, and tick the box marked add 5 percent extra for compaction and spillage.

For a garden with more than one job on the go, multiple areas holds up to five at once, and rectangle covers anything square-edged. Press calculate and the answer comes back in three units, with the option of having it emailed across as a written quote.

For that 20-foot ring at 2 inches, the form returns 1.94 cubic yards and about 2.6 tons, or 2.04 yards and 2.75 tons with the allowance ticked. Round it to 3 tons. The example, like every figure on this page, is invented to show the working.

Mason or washed: the choice that does not move the number

Mason sand is the finer, more even material, which is why it goes under pool liners, into mortar and into paver joints. Washed sand has had the clay and silt taken out of it and suits bedding, play boxes and general mixes. Both are published here at the same weight, so switching the material select between Mason Sand and Washed Sand changes the listing you buy from rather than the tonnage you worked out.

Two Maryland notes on the other common jobs. A play box wants washed sand at about 6 inches: a 6 by 6 foot box is 18 cubic feet, which is 0.67 of a cubic yard, or roughly 0.9 tons. For leveling a lawn, blend a quarter to a half inch of sand into soil rather than laying it straight, because over Piedmont clay a solid sand layer can stop roots passing through it; the soil half of that job is sized on the topsoil calculator. Mortar and concrete work to published ratios: allow roughly a ton of sand for every seven to eight bags of cement, and about a third of a ton of mason sand for a hundred-block wall.

If the job is a patio, this is the wrong tool. The one-inch bedding course under pavers is sized on the paver sand calculator, and the compacted stone beneath that on the paver base calculator.

Screeding the two inches, and what to do with the spare

Rake the sand out roughly, then pull a straight board across it on a slow arc to bring it flat. Damp sand screeds better than dry, which is the one time rain is on your side. Check for level in four directions across the ring, not two.

Keep the surplus back. A pool base always wants a wheelbarrow load more at one edge once the wall goes up, and whatever is left over does honest work in joints and low spots. Keep it covered.

Reading yards, tons and cubic feet at the end of it

Three numbers come back because three questions get asked. Cubic yards is the volume the job holds and the figure to use when you are working out whether two jobs share a load. Tons is what sand is sold by, so that is the entry for the quantity box. Cubic feet is the small-job unit: a 50 lb bag holds about half of one, which is why roughly 54 bags make a cubic yard and why anything past a dozen bags is worth ordering loose.

By hand it is three steps. Work out the area in square feet, which for a circle is the radius multiplied by itself and then by 3.14. Divide the depth in inches by twelve to get feet and multiply it through for cubic feet. Divide by twenty-seven for cubic yards, then multiply by the weight for the material.

Every figure there is approximate and comes from this site's own published chart. Take the tonnage to the listing, set the quantity and choose a date; delivery is arranged at checkout by ZIP code, and the delivery page sets out what the driver needs at the far end.

Common questions

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