An aggregate calculator answers two questions at once, because gravel, crusher run and base rock are ordered by the yard from some suppliers and by the ton from others: how many cubic yards the area needs, and how many tons that is for the material chosen. The yards are geometry, length times width times depth in feet divided by 27. The tons are the yards times the weight of a loose yard of that material, which the supplier states and which differs between a washed gravel, a crusher run with fines and a base rock. This page works both on a 30 by 20 foot pad at 6 inches, says where compaction changes the order, and points at the free concrete calculator on this site that does the slab's arithmetic on the same page, with no account.
The gravel volume calculator: yards from the area and the depth
Cubic yards of gravel equals length times width times depth, each in feet, divided by 27. A 30 by 20 foot pad is 600 square feet; at 6 inches, 0.5 feet, that is 300 cubic feet, 11.1 cubic yards. At 4 inches it is 7.4 yards; at 8 inches, 14.8. The depth is the compacted depth the base needs under the slab or the drive, and the loose depth spread from the truck is more, so the order carries a compaction allowance the material needs, commonly a fifth to a quarter more for a crusher run that packs tight. The rules on excavation and fill under a structure are the code's, published by the International Code Council; the arithmetic that turns the pad into an order is this page's.
The gravel ton calculator: tons from yards and the material's weight
Tons equals cubic yards times the weight of a loose cubic yard of the material, in tons, which the supplier states for each product. On the worked pad, 11.1 yards at a stated 1.4 tons per yard is 15.5 tons; at 1.5 tons per yard, 16.7. Crusher run, which carries fines, weighs more per yard than a washed and screened gravel of the same size, and a base rock with a wide gradation weighs more again, so the ton figure is only as good as the weight the supplier gives for the product ordered. A gravel tonnage calculator that carries one weight for everything is a guess with a decimal point; ask for the product's weight and use it.
Crusher run and base rock: what changes in the calculation
The geometry does not change; the compaction and the weight do. Crusher run and base rock are specified by the compacted depth under the slab, drive or footing, and they lose volume when compacted, so the loose yards delivered exceed the compacted yards in place by the allowance the material needs. The weight per yard is higher than a clean gravel's because the fines fill the voids. A crusher run calculator or base rock calculator is therefore the aggregate calculator with two numbers set for the product: the compaction allowance and the weight per yard. Both are the supplier's figures, entered once, and the order follows.
From the base to the slab: the two calculations together
The pad's base and the slab on it are worked from the same length and width, at different depths and with different units: the gravel in yards and tons at the base depth, the concrete in yards at the slab thickness. The free concrete calculator on this site takes the slab, 30 by 20 feet at 6 inches on the example, and gives 11.1 yards of concrete before waste; the base at 6 inches of crusher run is another 11.1 yards loose, more with compaction, ordered by the ton. Both lines go into the estimate at the supplier's prices, and both appear on the schedule of values when the slab is billed. Working them from one set of dimensions is what keeps the estimate and the draw agreeing.
Questions people ask about aggregate calculator
How does an aggregate calculator work?
Length times width times depth, in feet, divided by 27 gives cubic yards; yards times the material's weight per yard gives tons. A 30 by 20 foot pad at 6 inches is 11.1 yards, about 15.5 tons at 1.4 tons per yard.
Is crusher run calculated differently from gravel?
Same geometry, two different numbers: crusher run compacts more, so the loose order exceeds the compacted depth, and it weighs more per yard because of its fines. Use the supplier's compaction allowance and weight for the product ordered.
Why do gravel calculators give tons and yards?
Suppliers sell by either unit. The yards are the geometry; the tons are the yards times the weight per loose yard of that material, which differs between washed gravel, crusher run and base rock.