Rock calculator
Calculate this loadLarge stone has more voids than gravel. Use this when the yard calls it rock, riprap, or ‘landscape stone’ without a tighter name.
Project calculator
Area 1
Cubic yards
0.93 yd³
Tons
1.25 t
2 cu ft bags
13
Estimated cost
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Active area
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Rock planning density 1.35 t/yd³ (Generic decorative/riprap planning density). Order 1 yd³ with 5% waste. 3 cu ft bags: 9.
Rock is the word people type when they mean river rock, lava rock, riprap, or a yard’s ‘decorator stone’ pile. Those products do not share a density. A 6-inch cobble has air between the stones; 3/4-inch angular rock packs tighter. We publish 1.35 tons per cubic yard as a generic planning number and push you toward river rock, landscape rock, or crushed stone when you know the product.
Coverage is worse than the volume suggests. An inch of pea gravel hides soil. An inch of 4-inch cobble does not. For decorative rock, 2–3 inches is a veneer; 4 inches starts to look like a bed. Riprap on a slope is specified by stone diameter, not by a garden-center inch of cover.
If the project is a drainage swale, ask whether the yard wants clean washed stone or mixed. Fines clog fabric. If it is a fire pit apron, angular stone stays put; rounded river rock rolls underfoot.
Use related calculators for the specific stone. This page exists so a generic ‘rock calculator’ query still gets honest geometry and a cited density instead of a guess.
Formula
Yards = area × depth ÷ 27. Tons ≈ yards × 1.35 for mixed decorative rock.
Worked example
A 16 × 8 ft dry creek at 4 inches is 16 × 8 × 0.333 ÷ 27 = 1.58 yd³, about 2.1 tons.
Rock on the ground
Typical cover is 4 inches. Range 1.2–1.5 t/yd³. Size swings weight. Ask the yard for tons per yard on the specific stone.
Density table
| Material | t / yd³ | lb / yd³ | Source |
|---|---|---|---|
| River rock | 1.25 | 2500 | Supplier bulk tables for 1–3 inch washed river rock |
| Landscape rock | 1.3 | 2600 | Decorative rock planning weight, mid-range of washed stone |
| Rock | 1.35 | 2700 | Generic decorative/riprap planning density |
Related calculators
River rock calculator
Measure the bed, pick a depth at least as large as the stone, and convert to yards and tons at 1.25 tons/yd³.
Landscape rock calculator
Use this for mixed decorative stone when the yard has not given you a tighter product name or density.
Crushed stone calculator
Crushed stone is the angular base under driveways and pavers. Plan 4 inches, compacted, at about 1.35 tons per yard.