Landscape Rock Calculator
Find how much landscape rock you need for a bed, path, or ground-cover area. Enter the coverage length and width and the rock depth, pick a rock type, and get the volume in cubic yards, the weight in tons, the number of bags, and the cost by the ton — with by-depth and by-rock-type tables and a downloadable PDF.
| Depth | Cubic yards | Tons | Bags |
|---|---|---|---|
| Enter coverage to see depths | |||
| Rock | Density | Tons | Cost |
|---|---|---|---|
| Enter a volume to compare rock types | |||
How to use the landscape rock calculator
Enter the coverage length and width and the rock depth, pick a rock type, add a waste allowance, and get the volume in cubic yards, the weight in tons, the number of bags and the cost by the ton — with by-depth and by-rock-type tables and a downloadable PDF.
Enter the coverage
Length and width of the area in feet, inches or yards, and how many identical areas.
Set the depth
How deep the rock layer sits — 2–3″ is typical for decorative ground cover, deeper for paths.
Pick the rock type
River rock, pea gravel, crushed stone, lava rock, decomposed granite or cobbles — this sets the density.
Add waste, read & save a PDF
Get the cubic yards, tons, bags and cost, compare depths and rock types, and download it.
How the landscape rock estimate is calculated
Rock is ordered by volume but bought by weight. The math is three steps — area, then volume, then tons by the density of the stone — with a waste allowance added before you order.
Worked example — 20 × 12 ft bed, 3″ deep, river rock, 10% waste
Area: 20 × 12 = 240 sq ft
Volume: 20 × 12 × (3 ÷ 12) ÷ 27 = 2.22 yd³
With 10% waste: 2.22 × 1.10 = 2.44 yd³
Tons: 2.44 × 2,800 ÷ 2,000 = 3.42 tons
A 240-square-foot bed at 3 inches deep needs about 2.44 cubic yards of river rock — roughly 3.4 tons once waste is added.
Landscape rock reference charts
The numbers that come up most — how much a ton covers at each depth, how the tons change with depth, and how rock types compare by weight.
| Depth | Coverage / ton | Tons / 100 sq ft |
|---|---|---|
| 1 in | ~190 sq ft | 0.5 tons |
| 2 in | ~95 sq ft | 1.0 tons |
| 3 in | ~65 sq ft | 1.6 tons |
| 4 in | ~48 sq ft | 2.1 tons |
| 6 in | ~32 sq ft | 3.1 tons |
Based on river rock at about 1.4 tons per cubic yard. Deeper rock covers less area per ton, because each square foot holds more volume. Lighter stone like lava rock covers more area per ton.
| Depth | Cubic yards | Tons | 0.5 ft³ bags |
|---|---|---|---|
| 1 in | 0.81 yd³ | 1.1 tons | 44 |
| 2 in | 1.63 yd³ | 2.3 tons | 88 |
| 3 in | 2.44 yd³ | 3.4 tons | 132 |
| 4 in | 3.26 yd³ | 4.6 tons | 176 |
| 6 in | 4.89 yd³ | 6.8 tons | 264 |
Values rounded and include 10% waste. Notice how fast the bag count climbs — even a modest bed at 3 inches is over a hundred bags, which is why bulk delivery is almost always the better buy.
| Rock type | Weight | Notes |
|---|---|---|
| River rock | ~1.4 t/yd³ | Smooth, rounded; popular decorative cover |
| Pea gravel | ~1.4 t/yd³ | Small, loose; paths and fillers |
| Crushed stone | ~1.35 t/yd³ | Angular, locks together; bases and paths |
| Lava rock | ~0.75 t/yd³ | Lightweight & porous; far fewer tons |
| Decomposed granite | ~1.5 t/yd³ | Fine, compactable; heaviest per yard |
| Cobbles (3–8″) | ~1.45 t/yd³ | Large accent stone; needs more depth |
The volume is identical across types — only the tonnage changes. If you’re buying by the ton, lava rock buys far more coverage per ton than decomposed granite; by the yard or bag, they’re the same.
The amount of rock comes from three things: the coverage area and the depth set the volume, and the rock’s density turns that volume into a weight — the tons (or bags) you actually order.
- Area and depth set the volume — a bigger bed or a deeper layer means more rock, in direct proportion.
- Density sets the tons — the same volume weighs nearly twice as much in granite as in lava rock.
- Add waste, then order — allow ~10% for settling and edges, and buy in bulk once you pass a few bags.
Everything the calculator works out
One set of inputs gives you the volume in cubic yards, the weight in tons, the coverage area, the bag count and the cost — plus a comparison across depths and rock types, and a report to save.
The figures behind every order
Built for anyone laying landscape rock
A flower bed, a gravel path, a dry riverbed, a whole xeriscape — the area-depth-density math is the same, and knowing the tons and cost before you order means one delivery, no second trip, and no pile left over.
Covering a flower bed or garden path and wanting the right tonnage so one delivery finishes the job.
- Start at a 2–3″ depth
- Add 10% for settling
- Compare tons vs bags
Quoting a rock install across several beds and ordering bulk by the ton with a price built in.
- Add each bed as an area
- Price per ton for the quote
- Save the PDF to the job
Replacing lawn with rock and comparing stone types for weight, coverage and cost across the yard.
- Compare rock types by ton
- Lighter stone for big areas
- Plan fabric by the same area
7 tips for buying landscape rock right
The things that leave you short a ton or buried in bags — and the checks that get the order right the first time.
Landscape rock FAQ
The quantity, depth and buying questions people ask most when ordering rock for beds, paths and ground cover.
Multiply the length by the width by the depth — all in feet — then divide by 27 for cubic yards. For a depth in inches, divide the inches by 12 first. Then multiply the cubic yards by the rock’s density to get tons.
For a 20 by 12-foot bed at 3 inches deep, that’s 240 square feet, about 2.2 cubic yards, or roughly 3 tons of river rock before waste. The calculator does this for any size, depth and rock type, and adds your waste allowance.
Most landscape rock runs about 1.3 to 1.5 tons per cubic yard — river rock and pea gravel around 1.4, crushed stone near 1.35, and decomposed granite about 1.5. Lightweight lava rock is far less, roughly 0.75 tons per cubic yard.
That’s why the volume stays the same but the tonnage changes with the rock you pick. The calculator uses typical densities, but exact weight varies with size and moisture, so confirm with your supplier when ordering by the ton.
At a typical 1.4 tons per cubic yard and a 2-inch depth, one ton of river rock covers roughly 95 to 100 square feet. At 3 inches deep it covers about 65 square feet, and at 1 inch about 190 square feet.
Coverage drops as the depth goes up, because deeper rock means more volume per square foot. The calculator works from your exact depth, so you don’t have to rely on a rule of thumb.
A 2 to 3-inch depth is standard for decorative ground cover — enough to hide the soil or landscape fabric without being wasteful. Go a little deeper, 3 to 4 inches, for paths and high-traffic areas, and deeper still for driveways.
Smaller stone like pea gravel can sit shallower; larger cobbles need more depth to look right and stay put. The by-depth table shows how the tons and cost change as you adjust the depth, so you can find the right balance.
For anything larger than a small bed, bulk by the ton or cubic yard is far cheaper and less work than bags. Bagged stone — often 0.5 cubic feet per bag — makes sense only for small touch-ups, planters or spots a truck can’t reach.
As a rough guide, a cubic yard is about 54 of the 0.5-cubic-foot bags, so even a modest area adds up to a lot of bags fast. The calculator shows both the tonnage and the bag count so you can compare before deciding.
The volume you need is the same for any rock — it’s set by the area and depth. What changes is the weight: denser stone like decomposed granite weighs more per cubic yard, while lava rock weighs about half as much.
So if you buy by the ton, the rock type matters a lot for the tonnage and cost; if you buy by the cubic yard or bag, it barely matters. The tons-by-rock-type table compares them side by side for your volume.
Around 10 percent is a common allowance. It covers settling into the soil, uneven ground, spillage, and the extra needed to feather the edges and keep a consistent depth across the whole area.
Add a little more for very uneven ground or if you want a slightly deeper finish. It’s better to have a little extra than to come up short and pay a second delivery fee, so the calculator applies your waste percent on top of the raw volume.
Fabric under decorative rock helps suppress weeds and keeps the stone from sinking into the soil, which is why many installations use it — though it isn’t strictly required and the amount of rock you need is the same either way.
If you use fabric, a clean 2 to 3-inch rock layer over it hides it well and holds it down. The calculator sizes the rock itself; the fabric is a separate material measured by the same coverage area.
Estimate Only — Confirm With Your Supplier: This calculator finds volume from length × width × depth ÷ 27 and converts to tons using typical densities (river rock and pea gravel ≈ 1.4, crushed stone ≈ 1.35, decomposed granite ≈ 1.5, cobbles ≈ 1.45, and lava rock ≈ 0.75 tons per cubic yard). Actual weight varies with rock type, size and moisture, so add waste for settling and edging and round up. A 2–3 inch depth is typical for decorative ground cover; paths and driveways need more. For reference and estimating only; confirm coverage, tonnage and delivery with your landscape supplier before ordering.