Calculate how many tons of stone you need from length, width and depth, with typical densities for #57 stone, river rock and pea gravel, or find coverage.
Stone Formula
When you solve for the stone needed, the calculator finds the volume of the space you are filling, then converts that volume to weight using the material density.
Volume = Area * Depth
Weight = Volume * Density
When you solve for coverage instead, the calculator starts from a known weight and target depth and returns the area that weight will cover.
Area = Weight / (Density * Depth)
- Area: the surface you are filling, found from length and width, diameter, or a base and height depending on the shape you pick.
- Depth: how thick the stone layer is, converted to the same length unit as the area.
- Volume: area multiplied by depth, reported in cubic yards, cubic feet, or cubic meters.
- Density: the weight of the material per unit of volume, chosen from the stone type or entered directly.
- Weight: the result for a project estimate, or your input when you are solving for coverage.
The shape selector uses length times width for a rectangle, pi times radius squared for a circle, and one half times base times perpendicular height for a triangle. Material presets supply editable starting estimates of bulk density; replace them with the supplier value for your product and placement condition. Extra material multiplies the calculated volume and weight by 1 + extra percent / 100. It is an order allowance, not a measured compaction correction. Bags are rounded upward from the full unrounded weight divided by weight per bag. Per-bag cost uses that whole-bag count, including when only cost is requested; other cost bases use the unrounded estimated US tons or cubic yards. Material cost excludes tax, delivery and labor.
Stone Density and Coverage Reference
The existing ranges below are illustrative US short-ton estimates, not product specifications. Bulk density varies with gradation, voids, moisture and compaction. Confirm a supplier bulk-density value before ordering; solid-rock particle density is not interchangeable with loose bulk density. The calculator retains its original preset values as editable starting points and does not treat these ranges as validated standards.
| Stone material | Illustrative density (US tons/yd³) |
|---|---|
| Crushed stone #57 | 1.20 to 1.35 |
| Crushed stone #411 / river rock | 1.40 to 1.55 |
| Pea gravel / marble chips | 1.25 to 1.40 |
| Dense graded aggregate | 1.65 to 1.85 |
| Decomposed granite | 1.35 to 1.55 |
| Lava rock | 0.65 to 0.80 |
| Riprap / coarse rock | 1.30 to 1.50 |
One cubic yard of stone covers this much area depending on how thick you spread it.
| Depth | Coverage per cubic yard |
|---|---|
| 1 inch | 324 sq ft |
| 2 inches | 162 sq ft |
| 3 inches | 108 sq ft |
| 4 inches | 81 sq ft |
Example Problems
Example 1. You are covering a rectangular bed 20 feet long and 12 feet wide with 3 inches of crushed stone #57. The area is 20 times 12, or 240 square feet. The depth of 3 inches is 0.25 feet, so the volume is 240 times 0.25, which is 60 cubic feet, or 2.22 cubic yards. Using a custom bulk density of 1.3 US tons per cubic yard, that is about 2.89 US tons. Adding a 10 percent order allowance gives roughly 3.18 US tons. Select custom density and enter 1.3 US tons per cubic yard to reproduce this example; the original #57 preset is a different starting estimate.
Example 2. You have 5 US tons of pea gravel at a custom bulk density of 1.3 US tons per cubic yard and want to know the coverage at 2 inches deep. The volume is 5 divided by 1.3, or 3.85 cubic yards. At 2 inches deep each cubic yard covers 162 square feet, so 3.85 times 162 is about 623 square feet.
FAQ
How much extra stone should you order? Use the supplier or project specification for waste, placement and compaction. The optional 10 percent value is an editable example allowance, not a universal recommendation. A measured volume change may require a different correction; avoid counting the same compaction adjustment in both density and extra material.
Why does the calculator ask for a depth in inches when the area is in feet? It converts area and depth to compatible units before multiplying. Use the depth unit selector to match your measurement, and use the required finished depth from the supplier or project specification. This quantity estimate does not determine a suitable structural layer thickness.
Should you use tons or cubic yards when ordering? Confirm the supplier selling unit and bulk density. One US short ton is 2,000 lb; one metric tonne is 1,000 kg. A cubic yard measures volume, and its weight depends on bulk density and condition. The coverage solve uses the entered available weight and desired depth without adding an order allowance.
Sources
Unit definitions: NIST international-foot conversions and NIST SI conversion factors. Quantity-estimate context: Vulcan Materials aggregate estimator. These references do not validate the illustrative material presets or specify project compaction allowances.
