How many yards in a ton of gravel has no single answer, and that is the useful thing to know first: a ton is a weight, a yard is a volume, and the conversion is the weight of a loose cubic yard of the particular gravel, which the supplier states per product. At a stated 1.4 tons per yard, a ton is about 0.7 of a yard and a yard is 1.4 tons; at 1.5 tons per yard, a ton is 0.67 of a yard. The contractor calculating gravel needed works the yards from the area and the depth, then converts with the supplier's figure. This page says how big a yard of gravel is, works the conversion both ways, and does the whole calculation for a 30 by 20 foot pad; the free concrete calculator on this site works the slab that goes on top of it, with no account.
How big is a yard of gravel, and what it weighs
A yard of gravel is a cubic yard, 27 cubic feet, a cube three feet on each side, which covers 81 square feet at 4 inches deep or 54 square feet at 6 inches. What it weighs depends on the stone: a washed and screened gravel of one size has air between the stones and weighs less per yard than a crusher run whose fines fill the voids, and moisture adds to either. Suppliers state a weight per yard for each product because they sell by weight on a scale and by volume from a loader bucket; the National Institute of Standards and Technology's Handbook 44, linked below, is where the legal definitions of the ton and the yard live for the day two figures disagree.
How many tons of gravel in a yard, and yards in a ton, both ways
Tons in a yard is the supplier's weight per loose yard: 1.4 tons on the worked example, 1.5 for a heavier base rock. Yards in a ton is one divided by that: 1 divided by 1.4 is 0.71 yards, 1 divided by 1.5 is 0.67. So a ten-ton delivery at 1.4 tons per yard is 7.1 yards, and covers 580 square feet at 4 inches; at 1.5 tons per yard it is 6.7 yards and covers 540. The difference between the two weights on a ten-ton load is a third of a yard, which is a wheelbarrow or two, and on a hundred-ton job it is a truckload. Use the supplier's figure for the product ordered and the conversion is exact enough for the order.
How to calculate gravel needed: the worked pad
Length times width times depth, in feet, divided by 27, then times the weight per yard. A 30 by 20 foot pad is 600 square feet; at 6 inches compacted, 0.5 feet, that is 300 cubic feet, 11.1 cubic yards. At a compaction allowance of 20% for a crusher run, the loose order is 13.3 yards; at 1.4 tons per yard, 18.7 tons. Without the allowance the order is 15.5 tons and the base ends an inch short after the plate compactor has done its work. Calculating yards of gravel is those three steps, in feet, with the supplier's two figures, and the order is the result rounded up to the ton or the half yard the yard sells.
The base and the slab from one set of dimensions
The gravel base and the concrete slab share the pad's length and width and differ in depth and unit, so both are worked from one measurement. The free concrete calculator on this site takes the slab, 30 by 20 feet at 6 inches on the example, and returns 11.1 yards of concrete before the contractor's waste allowance; the base beneath it is the gravel sum above. Both go into the estimate at the supplier's prices, and both appear on the schedule of values when the slab is billed; the estimator on this site carries them as lines the owner can read, and the draw carries them as work in place.
Questions people ask about how many yards in a ton of gravel
How many yards are in a ton of gravel?
One divided by the supplier's weight per loose yard: about 0.71 yards at 1.4 tons per yard, 0.67 at 1.5. The figure is the product's, not a constant.
How many yards of gravel do I need for a 30 by 20 pad?
At 6 inches compacted, 11.1 cubic yards in place; with a 20% compaction allowance for crusher run, 13.3 yards loose, about 18.7 tons at 1.4 tons per yard.
How big is a yard of gravel in coverage?
27 cubic feet: 81 square feet at 4 inches deep, 54 square feet at 6 inches, before compaction.