Gravel Calculator

How the gravel calculator works out volume for each shape

Every version of this calculation starts the same way: find the footprint area in square feet, then multiply it by the depth. The three shape options only change how that first number, the area, is found. A rectangular area is simply length times width. A circular area, such as a round fire pit border or a circular planting bed, uses the standard circle formula, pi times the radius squared, with the radius being half of whatever diameter you measure across the circle. The third option skips the geometry entirely: if a site plan, a separate area calculator, or a landscaper's drawing has already given you a total square footage, typing that number in directly is both faster and no less accurate than re-deriving it from a length and width.

Once the area is known, depth turns it into a volume. Depth is usually described in inches, while length, width, and diameter are usually measured in feet, so the depth is first converted to feet by dividing by 12. Area (in square feet) times depth (in feet) gives a volume in cubic feet, which is the common unit every other figure on the results panel is converted from.

Working through a rectangular example makes this concrete. A 10 foot by 20 foot area is 200 square feet. Covered to a depth of 3 inches, converted to 0.25 feet, the volume is 200 times 0.25, or 50 cubic feet. From there the calculator converts that same 50 cubic feet into roughly 1.85 cubic yards (dividing by 27, the number of cubic feet in a cubic yard), about 1.42 cubic meters, and about 1,415.84 liters, all describing the identical volume of gravel in the units different suppliers, delivery slips, or bagged products might use.

How many cubic yard is 1000 sq ft? The table answers it for common areas and depths: at 3 inches deep, 1,000 square feet takes 9.26 cubic yards.

The two measurements most people get wrong are the depth and the area itself. Depth is easy to underestimate because 3 or 4 inches sounds thin when you picture it, but over a driveway-sized area that thin layer still adds up to several cubic yards, so it pays to measure it with a tape rather than guessing. Area is easy to get wrong when the space is not a clean rectangle or circle: an L-shaped path, a driveway that widens near the street, or a bed with several curved edges all need to be broken into sections first, with each section's volume calculated separately (using whichever shape option fits that section) and then added together.

How the weight is estimated, and why the density option matters

Weight is estimated by multiplying the cubic feet volume by a density figure, in pounds per cubic foot, for whichever material is selected. This is the step where the shape options and the density options work together: the geometry finds the volume, and the density turns that volume into a weight, which matters whenever a supplier prices by the ton rather than by the yard, or when you need to know how much a delivery truck or trailer axle will actually need to carry.

The density presets in the calculator convert to the tons-per-yard figures below, which is also how to turn yards to tons for a supplier's quote.

Continuing the same 50 cubic foot example with the default density option, gravel dry at 105 lb per cubic foot, the weight comes to 50 times 105, or 5,250 lb. Dividing by 2,000 lb per US ton gives about 2.63 tons. The same 5,250 lb converts to roughly 2,381.36 kilograms, or about 2.38 metric tons, again all describing the same physical pile of gravel. Switching the density dropdown to a heavier option, such as gravel with sand at 120 lb per cubic foot, or a lighter one, such as loose dry gravel at 95 lb per cubic foot, changes the weight and cost figures without touching the volume at all, since the volume depends only on the area and depth you measured, never on what material fills it.

It is worth being honest about the limits of any density figure, even a well-chosen one. Real gravel density varies with moisture content, how tightly it has settled or been compacted, and the exact mix of particle sizes in a given load. The options offered here are commonly published reference figures for each material type, useful planning numbers rather than a lab measurement of the specific truckload you are about to buy. For a small residential job the difference rarely matters much, but for a large or expensive order, it is worth asking your supplier what density figure they use for pricing and comparing it against the option you selected here.

A practical way to use this tool alongside a supplier's quote is to trust the volume figures most, since they come straight from your own measurements. Weight and cost are estimates built on top of that volume; if the supplier's density differs from every preset, hand them the volume and let them adjust the rest.

People search for this tool under many names. A stone calculator, rock calculator, river rock calculator, crushed rock calculator, aggregate calculator, yardage calculator and material calculator all ask the same question: volume from area and depth, then weight from a density. Gravel, crushed stone, pea gravel and river rock share the volume math and differ only in density. A dirt calculator or sand calculator uses the volume half too, but the weight half needs a density that this tool does not list.

What is gravel used for?

Gravel shows up in far more places than a driveway, and knowing the general category a project falls into is a useful sanity check on both the depth and the material you choose.

Construction. A compacted gravel base is standard underneath driveways, patios, sheds, and even building foundations, because a well-graded gravel layer compacts into a stable, load-bearing surface and drains water away rather than trapping it under a slab. Gravel and crushed stone are also a raw ingredient in concrete itself, mixed with sand, cement, and water as the coarse aggregate that gives cured concrete most of its bulk and compressive strength.

Landscaping and decoration. Gravel paths, mulch-replacement ground cover, dry creek beds, and decorative borders around planting beds all use gravel for looks as much as function: it needs no mowing or watering, suppresses weeds better than bare soil, and is available in enough colors and stone sizes to match almost any garden design. Pea gravel and small river stone are the two types most often chosen for this purpose, since their rounded edges are comfortable to walk on and do not shift as unpredictably underfoot as larger, angular stone.

Water treatment and agricultural uses. Graded gravel is a standard filtration layer in septic drain fields, French drains, and small-scale water treatment setups, where a specific range of particle sizes lets water pass through while trapping sediment. On farms, gravel is used to stabilize gateways, equipment yards, and barn aprons that would otherwise turn to mud under regular vehicle and livestock traffic, using much the same compaction logic as a residential driveway base, just at a larger scale.

Types of gravel

The gravel type you choose changes both its density (and so its weight and cost) and how well it performs for a given job. These five are the ones most commonly stocked by landscaping and construction suppliers.

Bank gravel. Dug straight from natural deposits along riverbanks and creek beds, bank gravel is an unwashed, ungraded mix of gravel, sand, and clay-like fines. Those fines are actually useful here: they let bank gravel compact into a firm, reasonably stable base, which is why it is a common, inexpensive choice for backfill and rough base layers, even though its look is far less uniform than a washed, graded product.

River stone. Naturally smooth and rounded from years of water erosion, river stone (sometimes called creek rock) ranges from small pebbles to fist-sized stones. Its rounded shape makes it comfortable underfoot and pleasant to look at, but also means it does not interlock or compact the way angular crushed stone does, so it is chosen for decorative beds and dry creek features rather than load-bearing bases.

Pea gravel. Small, rounded stones, typically around 3/8 of an inch across, pea gravel gets its name from its size rather than its color, and it is sold in a range of natural earth tones. It is a popular choice for walkways, playground surfacing, and as a decorative top dressing over soil or mulch, precisely because it stays comfortable to walk or play on while still draining well.

Crushed stone. Made by mechanically crushing larger rock, commonly limestone, granite, or trap rock, into angular fragments, crushed stone's jagged edges lock together far more tightly than any rounded gravel. That interlocking is exactly why it is the standard choice for driveway base layers, road sub-base, and drainage applications where the material needs to stay put under repeated weight rather than shift.

Pay gravel. A term borrowed from mining, pay gravel (or pay dirt) is gravel that holds enough recoverable gold or other minerals to be worth processing. It is not a construction or landscaping material, but it is where the idiom "hit pay dirt" comes from.