Mulch & Gravel Calculator

Estimate how much mulch, gravel, topsoil, sand, or bark you need for a rectangular area. Enter length, width, and depth to get cubic metres, cubic yards, cubic feet, and total surface area — so you can match the supplier's units exactly.

Examples

Garden bed — 5 × 3 m × 7.5 cm

A 5 m × 3 m garden bed mulched 7.5 cm deep — a common refresh depth for established beds.

Length: 5 m
Width: 3 m
Depth: 7.5
Depth Unit: centimetres (cm)

Volume Needed

1.13 m³

Same Volume, Other Unit

1.47 yd³

Cubic Feet

39.73 ft³

Surface Area

15 m²

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How It Works

Formula

V = L \cdot W \cdot D

V_{\text{yd}^3} = V_{\text{m}^3} / 0.764555

V_{\text{ft}^3} = V_{\text{m}^3} \cdot 35.3147

A = L \cdot W

Variables, symbols and units

$L$: Length
$W$: Width
$D$: Depth (layer thickness)
$V$: Volume of material
$A$: Surface area

Calculation method explained

Enter the length, width, and depth of the area you're covering. The calculator multiplies the three dimensions to get the volume in cubic metres, then converts to cubic yards (×1.308), cubic feet (×35.31), and computes the surface area separately. All three volume units are reported so you can order in whatever unit your supplier uses.

References and source material

Examples

Garden bed — 5 × 3 m × 7.5 cm5 m · 3 m → 1.13 m³

A 5 m × 3 m garden bed mulched 7.5 cm deep — a common refresh depth for established beds.

Length: 5 m
Width: 3 m
Depth: 7.5 cm

Volume Needed: 1.13 m³

Driveway base — 8 × 4 m × 10 cm8 m · 4 m → 3.2 m³

A gravel sub-base for an 8 m × 4 m driveway, 10 cm deep — typical for crushed stone over compacted ground.

Length: 8 m
Width: 4 m
Depth: 10 cm

Volume Needed: 3.2 m³

Pathway — 10 × 1 m × 5 cm10 m · 1 m → 0.5 m³

A 10 m × 1 m pathway with a 5 cm decorative gravel layer — enough cover without sinking footing.

Length: 10 m
Width: 1 m
Depth: 5 cm

Volume Needed: 0.5 m³

Frequently Asked Questions

Why doesn't this calculator output weight or tons?

Volume is unambiguous; weight is not. Mulch typically weighs 400–700 kg/m³ depending on the wood type, chip size, and moisture. Gravel runs 1,500–1,700 kg/m³ depending on stone type and compaction. Picking one density would mislead anyone whose material falls outside it. Order by volume — what your supplier actually sells — and use their published density spec if you need a weight estimate.

How deep should I lay mulch or gravel?

Mulch on garden beds is usually 5–10 cm (2–4 in) deep — enough to suppress weeds and retain moisture without smothering roots. Decorative gravel paths run 3–5 cm (1–2 in). A gravel sub-base under paving or a driveway is 10–15 cm (4–6 in) of compacted crushed stone. Going deeper wastes material; going shallower defeats the purpose.

How is bulk material sold — by yard³ or m³?

It depends on the country. Suppliers in the US and Canada usually sell by the cubic yard (yd³); UK, EU, and most of the world sell by the cubic metre (m³). Bagged material is sold in cubic feet, litres, or bag count. This calculator gives you all four (m³, yd³, ft³, plus area) so you can match whichever your supplier uses.

How do I compact gravel after laying it?

For a sub-base, lay the gravel in 5–8 cm (2–3 in) lifts and compact each lift before adding the next. A plate compactor (rentable from any tool-hire shop) is the standard tool for driveways and patios. Manual tampers work for small paths. Compacted gravel loses 15–25% of its loose volume — order extra if compaction matters for your project.

Should I add extra for waste or settling?

For mulch laid loose, the calculator volume is what you need. For gravel that will be compacted, add 15–25% extra. For irregular areas (curved beds, slopes), add 5–10% to account for the difference between the bounding rectangle and the actual footprint. Suppliers can usually deliver an extra half-yard or quarter-cubic-metre on request.

Mulch & Gravel Calculator

Garden bed — 5 × 3 m × 7.5 cm

How It Works

Examples

Frequently Asked Questions

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