Measure the path, the bed or the drive and this gives you the cubic yards, the tons and the bags — for the stone you actually chose, at its own published weight. A drive is two layers, so work them out one at a time and add them up.
300 sq ft at 3″ of pea gravel (3/8″)
2.8 cubic yardsThat is 75 cu ft, or 150 bags of 0.5 cu ft. One cubic yard covers 108 sq ft at this depth.
- Area
- 300 sq ft
- Depth
- 3″
- Volume
- 2.78 cu yd (75 cu ft)
- Bags of 0.5 cu ft
- 150
- Weight
- 3.8 tons
Stone is heavy and a delivery is final: two tons in the wrong place is a weekend with a shovel. Check where the truck can tip before you order, and remember that a yard of wet stone weighs about a third more than the same yard dry.
Weights and layer rules checked 2026-09-24.
Quick answer: a cubic yard of stone covers 324 sq ft at 1 inch, 162 at 2 inches and 108 at 3 inches, and weighs between 2,565 and 3,375 lb depending on which stone it is and whether it is wet (published figures, EPA & NTEA). So a 30 × 10 ft path at 3 inches is 2.8 cubic yards, about 3.8 tons of pea gravel. The rule that decides the depth is the FHWA’s: a layer must be at least twice as thick as its biggest stone.
How to use it
Measure the area, pick the stone and set the depth for one layer. The answer comes in cubic yards (what a supplier quotes), tons (what a supplier sometimes charges) and bags (what fits in a car). Every stone on the list carries its own published weight per cubic yard, so switching from pea gravel to river rock changes the tonnage without changing the volume — which is exactly the mistake a single-density calculator hides.
For a drive, run it twice: once for the base and once for the surface. They are different stones doing different jobs, and adding a deeper layer of the same stone is not a substitute.
What a yard of each stone weighs
| Stone | Per cubic yard | 100 sq ft at 2″ |
|---|---|---|
| Pea gravel (3/8″) | 2,700 lb | 0.62 yd³ · 0.83 tons |
| 3/4″ gravel | 2,565 lb dry / 3,375 lb wet | 0.62 yd³ · 0.79–1.04 tons |
| Crushed stone | 2,700 lb | 0.62 yd³ · 0.83 tons |
| Crushed limestone | 2,565 lb | 0.62 yd³ · 0.79 tons |
| River rock (2–6″) | 3,200 lb | 0.62 yd³ · 0.99 tons |
Those weights are from the published Cubic Yardage Chart, whose own note says the figures were gathered from the EPA and the NTEA. The chart lists ¾” gravel twice — dry and wet — and the gap between them is the useful part: the same stone is about a third heavier after rain.
How deep, and why “twice the stone” matters
The FHWA’s Gravel Roads Construction and Maintenance Guide states it plainly: “A general rule is the minimum thickness when placing each layer of gravel is twice the thickness of the top-sized stone.” Spread a layer thinner than that and the stones have nothing to lock against — they roll, they scatter, and the surface never firms up. In practice:
- Pea gravel (3/8″) — at least ¾ inch in a pass; 2 inches is the usual finished depth for a path.
- 3/4″ stone — at least 1½ inches in a pass.
- 2″ rock — at least 4 inches. This is why a “decorative river rock” bed swallows so much more material than people expect.
- Stone as a mulch in a planting bed — Clemson gives 1 inch for weed control, which is a third of what bark needs.
A drive is two layers, not one deep one
The same FHWA guide separates the jobs: “A higher percentage of large stone is needed for strength in the base course, but will be detrimental to surface gravel.” The base carries the load and wants coarse, angular stone; the surface wants the finer, binding material that sheds water and is comfortable to walk and drive on. A single deep layer of rounded pea gravel over soil is the classic home-drive mistake, and the ruts show up in the first wet month.
So work it out as two numbers: base depth in coarse crushed stone, then the surface depth in the finer material. Run the calculator once for each and order both.
Yards or tons?
Ask the supplier which they are selling. A cubic yard is a fixed volume; a ton is a weight, and how much stone that buys depends on the stone and the weather. With ¾” gravel published at 2,565 lb dry and 3,375 lb wet, a ton bought after a week of rain is roughly a quarter less stone than a ton bought in a dry spell. Neither is dishonest — they are simply different units — but comparing a yard price with a ton price without converting is how two quotes stop being comparable.
Before the truck arrives
- Know where it is going. A tipper needs headroom and a hard standing; stone tipped on a lawn stays on the lawn.
- Order a little over. Nothing here adds a compaction or waste factor, because none is published — but stone beds down as it is walked and driven on, and a second delivery costs another delivery fee.
- Fabric under stone, on soil. Otherwise the stone works its way down into the ground and the weeds work their way up.
- Edge it. Loose stone migrates. Anything without an edge ends up in the grass and then in the mower.