GRAVEL
Gravel calculator
Cubic yards of gravel = square feet × depth in inches ÷ 324, and cubic feet = square feet × depth in inches ÷ 12. Those two lines answer the question for any gravel job, because gravel is a volume product everywhere except at the till, where it is often sold by weight. The volume answer is immediate; the tonnage question is handled honestly further down.
Worked example
A 300 sq ft driveway at 4 inches: 300 × 4 ÷ 12 = 100 cubic feet, and 300 × 4 ÷ 324 = 3.70 cubic yards.
In bags, divide by the bag volume and round up. A common retail bag is 0.5 cubic feet (sold as a 50 lb bag of pea gravel), so 100 ÷ 0.5 = 200 bags. That is the arithmetic — and it is also the argument for buying bulk, because 200 bags is a pallet-and-a-half of carrying for less than four cubic yards of material.
Tons: why this calculator will not give you a number
Gravel is frequently priced by the ton rather than the yard, and converting volume to weight needs the density of the specific aggregate — which varies by rock type, by gradation (pea gravel, crusher run, and #57 stone are all different), and by moisture. A density figure taken from a different product can be wrong by a wide margin, and the error lands on your invoice.
So the honest instruction is: calculate cubic yards here, then ask the supplier for their conversion for that product, or ask them to quote in cubic yards. If they quote tons and you want to check it, ask them for the pounds per cubic yard they used and do the multiplication yourself — this page will not supply a number it cannot stand behind.
Depth is set by the job, not by the material
Unlike mulch, gravel depth is an engineering choice that depends on what the gravel is doing and what is underneath it: a decorative border, a walking path, a driveway sub-base and a drainage trench all want different depths, and a driveway over soft ground wants more than the same driveway over compacted hardcore. Those figures come from your project, your local building requirements, or a contractor — not from a generic table. Measure the depth your job needs and put it in the formula.
Ordering in bulk: what to have ready
- Cubic yards, from the formula above.
- Depth in inches, and whether that is loose depth or compacted finished depth — compaction reduces thickness, and sub-base gravel is compacted.
- The product name and gradation, because that is what determines the weight per yard.
- Access: a cubic yard of gravel is roughly a ton and a half of material, so where the truck can stand is part of the order.
- Waste allowance. Add a percentage for spreading loss and for an uneven subgrade; decide the percentage yourself rather than accepting one silently.
Related calculators
The mulch calculator runs the same volume arithmetic for a lighter material, and the coverage calculator handles a rectangular area with a circular section removed — the same subtraction you need for a gravel pad with a planting island in it.
Sources: Bag volume is 0.5 cubic feet / 50 lb, the common retail size for bagged pea gravel. The arithmetic is from the definitions 1 cubic yard = 27 cubic feet and 1 foot = 12 inches.
Cite this dataset
The mulch coverage, bag-count and dated price tables from this site are archived as a citable dataset: Mulch coverage, bag-count and dated bulk price tables, version v1, published 20 September 2026, 9 files, creator ERTHK — DOI 10.5281/zenodo.22855990, record at zenodo.org/records/22855990.
Released under CC0 1.0 Universal (Creative Commons Zero v1.0 Universal): free to copy, modify and redistribute.
The source library that generates the tables, with its test suite, is at github.com/ERTHK/mulch-measure-calculator-kit, released under the MIT license.