Sand Calculator

How to Use the Sand Calculator

Sand is measured as a volume and sold as a weight, and the conversion between the two moves by a third depending on how wet the pile is. That single fact is why sand orders go wrong, and it is the thing this page is built to make visible.

1. Measure the area and the depth. Length and width in feet, depth in inches. A paver bedding course is usually one inch; a sandbox six to twelve; a base layer under a pool or a patio somewhere between.
2. Pick the condition of the sand. Dry loose runs about 90 lb per cubic foot, dry 100, damp 110 and wet or packed 120. This is the figure the supplier's tonnage is derived from.
3. Add both prices if you have them. A price per ton and a price per bag together tell you which way of buying is cheaper, which is rarely obvious from the shelf.
4. Order to the volume, check against the weight. The cubic-foot figure is what your excavation holds and it is close to exact. The tonnage is a conversion with real uncertainty in it.

Everything runs in your browser. Nothing about the job is transmitted or stored.

Sand Volume and Weight Formulas

A volume, a density and two unit conversions. The only genuinely uncertain term is the density.

The density range is not a rounding question. Dry loose sand at 90 lb per cubic foot and wet packed sand at 120 differ by a third, and the same hole filled with either takes the same volume but a very different weight. Since you buy by weight and measure by volume, that spread lands entirely on you.

Damp sand behaves oddly and it is worth knowing why. Water films between grains hold them apart — the effect that makes sandcastles possible — so slightly damp sand is actually bulkier per pound than dry sand until it is saturated, at which point the water fills the voids and the weight climbs sharply.

Example

Worked example one: a 20 ft by 10 ft paver bed, 2 inches deep. The area is 200 square feet, and two inches is 2 ÷ 12 = 0.16667 feet, so the volume is 200 × 0.16667 = 33.33 cubic feet. That is 33.33 ÷ 27 = 1.235 cubic yards, or 0.944 cubic metres.

At dry sand's 100 lb per cubic foot the weight is 33.33 × 100 = 3,333 lb, which is 1.667 US tons or 1.512 metric tonnes. In 50 lb bags that is 3,333 ÷ 50 = 66.67, so 67 bags. At $32 a ton bulk costs 1.667 × 32 = $53.33; at $5.98 a bag, bags cost 67 × 5.98 = $400.66.

Bulk is seven and a half times cheaper. Bagged sand is priced for convenience and for people buying two bags, and at sixty-seven bags that convenience costs $347 and several car journeys.

Worked example two: the same hole in different weather. The volume does not change — 33.33 cubic feet is 33.33 cubic feet. But dry loose sand at 90 lb per cubic foot weighs 3,000 lb, or 1.500 tons, while wet packed sand at 120 weighs 4,000 lb, or 2.000 tons.

That is a spread of half a ton, or 33%, on an identical excavation. At $32 a ton it is a $16 difference — small here, but on a twenty-ton order it is $320, and it is entirely invisible if you order by weight without asking what condition the pile is in.

Volume Is Certain, Weight Is Not

Read the volume as the reliable number and the tonnage as the negotiable one. Your excavation holds 33.33 cubic feet whatever the weather, and that figure will not change. What it weighs, and therefore what you pay, depends on a density you did not choose and cannot easily verify.

The bulk-versus-bags comparison usually resolves itself. Bags win only for very small jobs — a few square feet of bedding, a repair, a planter — where the delivery minimum and delivery fee would dominate. Anywhere above roughly half a ton, which is twenty bags, bulk is dramatically cheaper.

Depth deserves care because sand is often specified precisely. A paver bedding course is meant to be one inch after screeding and it should not be used to correct an uneven base — thicker bedding sand allows pavers to sink unevenly under load, which is the most common cause of a rippled patio a year later.

Different jobs want different sand, and the names are inconsistent between suppliers. Sharp or concrete sand for bedding and mixing, fine washed sand for a sandbox, kiln-dried jointing sand for filling paver joints. Buying the wrong one is a bigger error than getting the tonnage slightly out.

The gravel calculator covers the sub-base beneath a sand bedding layer, and the concrete calculator handles the slab if the design moves that way.

Five Things That Change the Delivery

Five things that change what turns up on the driveway.

Moisture at the time of loading. The single biggest variable. A yard that stores sand outdoors will load a heavier ton after rain, and you are paying for water that drains away within days of delivery.

Compaction. Sand settles when vibrated or walked on, typically by ten to fifteen per cent for a bedding layer. Specify the depth you want after compaction and add for it, or you will be a bag short at the last row of pavers.

Grade names vary regionally. Sharp sand, concrete sand, bedding sand, grit sand and builder's sand overlap heavily and mean different things in different places. Describe what you are using it for rather than naming a grade, and let the supplier translate.

Delivery minimums. Most yards will not deliver less than a ton, and many set the minimum at three or more, plus a flat delivery charge. On a job needing 1.67 tons, that charge can be a larger share of the bill than the sand.

Screeding takes practice, not extra sand. A bedding layer is levelled by dragging a straightedge along two rails set to the finished depth, and the sand pushed ahead of it goes back into the next section rather than being wasted. The common instinct to order extra because levelling looks wasteful is misplaced — almost nothing is lost, and what is lost sits in the barrow.

What does get wasted is sand spread over an area that then has to be lifted and relaid because the base was not compacted first. That is a base problem rather than a sand problem, and no allowance on this page will fix it.

Play sand is a different product. Sand sold for sandboxes is washed and screened to remove silt and fine dust, and it is priced accordingly. Using ordinary building sand for a child's sandbox is not a saving worth making, and the volume calculation is the only part of this page that carries over.