How this instrument works
Landscape rock is sold and delivered by weight, but you plan a bed by area and depth — so this calculator bridges the two: it converts your bed's length × width × depth into cubic yards, then multiplies by a density figure to get tons. That two-step conversion, volume to cubic yards then cubic yards to tons, is how every stone yard and landscape supplier prices and delivers bulk material.
Density is the part that genuinely varies, and it's exposed here as an editable input rather than baked in as a fixed constant. Decorative landscape rock runs lighter than crushed aggregate on average — commonly around 1.2 to 1.5 tons per cubic yard — because larger, rounder decorative stone packs with more air gaps between pieces than angular crushed gravel does. The 1.3 tons/yd³ default here is a reasonable middle-of-the-road planning figure, not a promise about the specific rock you're buying; ask your supplier for their product's actual density, or weigh a sample load, before ordering a large quantity.
Depth recommendations also vary by purpose: a thin 1.5-2 inch decorative topping over a flower bed uses far less material than a 3-4 inch layer meant to suppress weeds, or a 4-plus inch layer under a walkway. Pick a depth that matches what you're actually trying to achieve, since depth affects the tonnage as directly as the footprint area does.
- Enter Area length (ft) and Area width (ft) — the footprint of the bed or area you're covering.
- Enter Depth (in) — how thick a layer of rock you want, commonly 2-4in for decorative beds.
- Enter Material density (tons/yd³) — check with your supplier for your specific rock's actual figure; 1.3 is a typical decorative-rock planning default.
- Read Volume (cubic yards) and Landscape rock needed (tons) — the amount to order.
Worked example — a 15×8 ft garden bed
Set Area length to 15 ft, Area width to 8 ft, Depth to 3in, and Material density to 1.3 tons/yd³, a typical figure for decorative landscape rock. Volume = 15 × 8 × (3/12) = 30 cu ft ÷ 27 = 1.1111 cubic yards. Tons needed = 1.1111 × 1.3 = 1.4444 tons.
That's the order quantity for this one bed. A larger 30×12 ft bed at a thinner 2in layer, using lighter rock (1.2 tons/yd³) near the low end of the typical range, needs 2.2222 cubic yards and 2.6667 tons — proportionally less per square foot than the first example because both the depth and the density dropped.
Questions
How much does landscape rock weigh per cubic yard?
It varies by rock type and size, but decorative landscape rock commonly runs around 1.2 to 1.5 tons per cubic yard — lighter than angular crushed stone, which tends toward 1.4 to 1.7 tons/yd³, because larger and rounder decorative stone leaves more air gaps when it settles. Ask your specific supplier for their product's density, or weigh a small sample load, if you need a precise figure for a large order.
How deep should a layer of landscape rock be?
It depends on the purpose. A purely decorative topping over mulch or fabric often only needs 1.5-2 inches; a layer meant to help suppress weeds or provide meaningful ground cover typically runs 2-3 inches; and a functional layer under a walkway or drainage area often goes 3-4 inches or more. Deeper isn't automatically better — too much depth can bury smaller plants and wastes material, so match the depth to what the area is actually for.
Why does the calculator ask for density instead of using one standard number?
Because there isn't one standard density for landscape rock — it depends on the specific stone's size, shape, and mineral composition. River rock, lava rock, decorative gravel, and larger boulders can all carry meaningfully different weights per cubic yard, so a single hardcoded number would be wrong for a large share of real orders. Entering your supplier's actual figure, or a reasonable estimate for your rock type, gives a far more accurate tonnage than any single universal constant could.
Should I order extra rock beyond the calculated tonnage?
Many people add a small buffer, especially for irregular bed shapes that don't match a clean rectangle, or when the exact depth is hard to control during spreading. This calculator computes the geometric minimum for the area and depth you enter; if your bed has curves, slopes, or an uneven base that will eat extra material, padding the order by 5-10% is a reasonable practical habit.
Does this work for other bulk materials besides landscape rock?
The math — area × depth ÷ 27 to get cubic yards, then cubic yards × density to get tons — applies to any bulk aggregate: gravel, mulch, sand, topsoil, and similar materials all use the same volume-to-weight conversion. The only thing that changes between materials is the density figure, so if you know your specific material's tons-per-cubic-yard, this same formula works for it too.