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Landscape Rock Calculator

Work out how much landscape rock a bed or border needs — volume in cubic yards and weight in tonnes, with the density set from your supplier's figure.

Rock is heavy, expensive, and sold by the tonne — so the weight matters as much as the volume. This calculator gives you both, and the density is yours to set from the supplier.

The default 1,600 kg/m³ is typical for decorative rock. Granite runs heavier, sandstone lighter — use your supplier's figure when you have it.

Rectangle only — leave blank for a circle or a known area.
Circle only.
Use this only if you already know the area.
Decorative rock is usually spread 2–3 in deep.
10% covers uneven spreading.
Typical decorative rock is about 1,600 kg/m³ — change this to your supplier's figure. Rock density varies a lot by stone type.
Enter your local price — the calculator never guesses prices.

Formula

area = length × width (rectangle) or π × (diameter ÷ 2)² (circle) volume = area × depth weight = volume × density weight in tonnes = volume (m³) × density (kg/m³) ÷ 1,000 Default density 1,600 kg/m³ is a typical figure — change it to your supplier's.

All lengths are converted to a single unit before the calculation: 1 ft = 0.3048 m, 1 in = 25.4 mm, 1 ft² = 0.09290304 m², 1 yd² = 9 ft². Material quantities are rounded up — you cannot buy part of a tile, plank or bag.

How to use this calculator

  1. Choose the shape of the area (rectangle, circle, or a known area).
  2. Enter the depth — 2–3 in is normal for decorative rock.
  3. Check the density against your supplier's figure (default 1,600 kg/m³).
  4. Add a price per tonne if you want a cost estimate.

Worked example

Area10 ft × 10 ft = 100 ft²
Volume (2 in deep)100 × ⅙ ft = 16.67 ft³ = 0.62 yd³
With 10% wastage0.62 × 1.10 = 0.68 yd³ (0.52 m³)
Weight (1,600 kg/m³)0.52 × 1,600 = 830 kg = 0.83 tonnes

Check it by hand: every step above uses the formula in the box. If your numbers match the example inputs but the calculator gives a different answer, please report it via the contact page.

Frequently asked questions

How much does landscape rock weigh?

It depends on the stone — granite is heavier than sandstone, and wet rock is heavier than dry. A typical figure is 1,600 kg/m³, but your supplier's figure is the one to use. This calculator defaults to 1,600 and lets you change it.

How deep should landscape rock be?

2–3 in (50–75 mm) over a weed membrane is standard for decorative beds. Less shows the membrane; more is a waste of expensive stone.

Is landscape rock sold by weight or volume?

Usually by the tonne for bulk orders and by the bag for small ones. This calculator gives you both the volume and the weight, so you can compare quotes either way.

What is the difference between landscape rock and pea gravel?

Landscape rock is larger, angular stone (20–50 mm) used as a decorative cover. Pea gravel is small, rounded stone (5–10 mm) used for paths and drainage. Use the pea gravel calculator for that.

Related calculators

Estimates only. Results are for planning. Measure twice, confirm box coverage and tile sizes on the packaging you buy, and follow the manufacturer's instructions. See the disclaimer.