Free · Nine materials, every density published
Landscape Rock Calculator
Cubic yards and tons for any area and depth, in square feet or meters. Below it, what a yard of rock actually weighs for nine materials, because the figure moves two to one between lava rock and crushed stone.
The short answer
How much landscape rock do I need?
Area in square feet, times depth in feet, divided by 27 for cubic yards. Multiply by the material's tons per cubic yard for weight. A 200 square foot bed at 3 inches is 1.85 cubic yards, or 2.50 US tons of river rock.
Add about 10 percent for settling and spillage, which takes that job to 2.04 cubic yards. The figure that catches people out is not the arithmetic, it is the weight per yard, which is not the same for any two materials.
The reference
How much does a cubic yard of rock weigh?
| Material | lb per ft³ | lb per yd³ | US tons per yd³ |
|---|---|---|---|
| Pea gravel | 100 | 2,700 | 1.35 |
| River rock | 100 | 2,700 | 1.35 |
| Crushed stone #57 | 104 | 2,808 | 1.40 |
| Crushed stone #411 | 100 | 2,700 | 1.35 |
| Decomposed granite | 104 | 2,808 | 1.40 |
| Stone dust | 104 | 2,808 | 1.40 |
| Marble chips | 96 | 2,592 | 1.30 |
| Lava rock | 52 | 1,404 | 0.70 |
| Screened topsoil | 74 | 1,998 | 1.00 |
Rock is sold by the ton and spread by the yard, so this table is the bridge between the two. A ton of lava rock is about 1.4 cubic yards. A ton of crushed stone is about seven tenths of one. Order the same tonnage of each and you get very different amounts of ground covered.
Every figure here is loose and dry. Compacted material is denser, and wet material runs roughly 8 percent heavier. The full dataset, with sources and caveats, is published as open data under CC BY 4.0.
Coverage
How many square feet does a ton of rock cover?
| Material | 2 in | 3 in | 4 in | 6 in |
|---|---|---|---|---|
| Pea gravel | 120 | 80 | 60 | 40 |
| River rock | 120 | 80 | 60 | 40 |
| Crushed stone #57 | 115 | 77 | 58 | 38 |
| Crushed stone #411 | 120 | 80 | 60 | 40 |
| Decomposed granite | 115 | 77 | 58 | 38 |
| Stone dust | 115 | 77 | 58 | 38 |
| Marble chips | 125 | 83 | 62 | 42 |
| Lava rock | 231 | 154 | 115 | 77 |
| Screened topsoil | 162 | 108 | 81 | 54 |
Coverage is the inverse of weight, so the lightest rock goes furthest. One ton of lava rock covers 154 square feet at 3 inches where crushed stone covers 77, which is the whole reason lava rock sells by the bag and crushed stone by the truck.
Choosing
Landscape rock types and what each one is for
| Material | What it is | Use it for |
|---|---|---|
| Pea gravel | Rounded 3/8 in | Paths, patios, play areas |
| River rock | Rounded 1 to 3 in | Dry creek beds, drainage, borders |
| Crushed stone #57 | Angular 1/2 to 1 in | Drains, driveway surface |
| Crushed stone #411 | Angular, with fines | Compacted base |
| Decomposed granite | Fine grit and dust | Paths that need a firm surface |
| Stone dust | 1/4 in and down | Paver setting bed |
| Marble chips | Angular white | Formal beds, reflective ground cover |
| Lava rock | Porous, vesicular | Mulch replacement, fire features |
| Screened topsoil | Soil, not rock | Beds and lawn repair |
The dividing line is angular against rounded. Angular stone such as crushed stone and decomposed granite locks together, so it holds on a slope and carries weight. Rounded stone such as river rock and pea gravel rolls, which makes it comfortable underfoot and useless as a base.
That single property decides most choices. A driveway needs angular stone underneath whatever you see on top. A slope above about 5 percent needs angular stone or the rounded kind migrates downhill. A path people walk barefoot wants the rounded kind.
Dedicated calculators cover the common materials in more depth: pea gravel, river rock and crushed stone.
Driveways
Working out rock for a driveway
| Depth | Cubic yards | US tons at 1.40 | Typical use |
|---|---|---|---|
| 2 in | 0.62 | 0.86 | Topping up an existing drive |
| 4 in | 1.23 | 1.73 | Light use base |
| 6 in | 1.85 | 2.59 | Heavy use base |
A driveway wants 4 to 6 inches of compacted angular stone, and dense graded material loses 20 to 25 percent of its loose volume as it is rolled, so order that much more than the finished dimensions suggest. The crushed stone calculator covers the grades and the layered build.
Questions
Landscape rock FAQ
Most landscape rock runs about 2,700 lb per cubic yard, or 1.35 US tons. Crushed stone and decomposed granite are heavier at roughly 2,800 lb, marble chips lighter at 2,592, and lava rock far lighter at about 1,404 lb because the stone is full of gas bubbles.
About 120 square feet at 2 inches deep, 80 at 3 inches and 60 at 4 inches, for rock at 100 lb per cubic foot. Lava rock covers roughly twice that ground per ton, and crushed stone slightly less, because coverage follows weight.
Multiply the area in square feet by the depth in feet, then divide by 27. A 200 square foot bed at 3 inches deep is 50 cubic feet, which is 1.85 cubic yards, or 2.04 once you add a 10 percent allowance for settling and spillage.
Lava rock, by a wide margin, at about 52 lb per cubic foot against 100 for most stone. A cubic yard weighs roughly 1,404 lb rather than 2,700, which is why it is the usual choice where weight matters, such as over a roof deck or a drainage layer.
About 1,404 lb, or 0.70 US tons, at 52 lb per cubic foot. Many landscape suppliers list lava rock near 100 lb per cubic foot, which is close to double the real figure. Check whether your supplier is quoting by volume or by weight before ordering.
Four to six inches of angular stone, which is 1.23 to 1.85 cubic yards per 100 square feet before compaction. Rounded rock such as river rock or pea gravel will not lock together under tires, so a driveway needs crushed stone or crusher run instead.
Open graded angular stone such as #57, which has roughly 36 to 42 percent voids and lets water pass straight through. River rock also drains well and looks better above ground. Avoid anything containing fines, because the dust fills the gaps and blocks flow.
Yes, by roughly 8 percent for most aggregate, and considerably more for porous stone such as lava rock, which absorbs water into its gas pockets. Quarries quote dry weight, so a wet delivery can read heavier on the ticket than the volume you receive.
Transparency
Sources and methodology
- Densities. Loose and dry, in lb per cubic foot, published in full as open data with per-material caveats. Background from USGS Mineral Commodity Summaries 2026, Stone (Crushed) (PDF) and Sand and Gravel (Construction) (PDF).
- Lava rock at 52 lb/ft³. Roughly half the weight of most aggregate, because the stone is vesicular. Landscape suppliers frequently list it near 100, which is close to double the real figure, and it is the single most common density error in this category.
- Topsoil at 74 lb/ft³. Dry and screened. Published figures run 1,500 to 2,200 lb per cubic yard, and saturated soil can reach 3,000, so this is the widest range in the table.
- Coverage. Derived arithmetic, 2,000 lb divided by density gives cubic feet per ton, divided by depth in feet gives square feet. Loose, before compaction.
- Wet weight, plus 8 percent. A general figure for aggregate. Porous stone such as lava rock absorbs considerably more.
Need the numbers as a file?
Every density on this page is published as open data under CC BY 4.0, with sources and the caveats that come with each figure.