GARDEN & OUTDOORS

Mulch Calculator

A few garden spaces. One clear shopping list.
Combine areas, choose your depth, and see the bags or bulk volume you need.

Your garden spaces

Enter net areas to cover. Exclude paths and gaps, and count overlapping areas only once. Use a decimal point, for example 1.5.

Up to 10 areas

Use the volume on your bag. Extra allowance is optional, from 0–30%; none is added by default. Depth is your choice, not a planting recommendation.

Your mulch estimate

A uniform mulch layer over soil. Diagram not to scale.Your chosen depthExisting ground
Diagram not to scale

A little measuring.
A garden-ready estimate.

Add your areas and a shared depth to begin.

MEASURE THE SURFACE

How much mulch do I need?

Mulch covers the ground in a layer. Measure each rectangular area, or enter a known net area for an irregular space. Subtract paths, paving and gaps before entering it. Split an irregular outline into non-overlapping shapes and add their areas.

The calculator adds every area and applies one uniform depth. It does not detect overlaps or subtract obstacles automatically. Different depths require separate calculations.

The formula, made visible.

US: cubic feet = total square feet × depth in inches ÷ 12.

Metric: liters = total square meters × depth in centimeters × 10.

Purchase volume = base volume × (1 + extra allowance ÷ 100). Divide by bag volume and round up once, after combining all areas.

Two areas measuring 10 × 12 ft and 5 × 6 ft total 150 ft². At 3 in deep, they need 37.5 ft³ (1,061.882 L), or 19 bags of 2 ft³. With 10% extra: 41.25 ft³ and 21 bags.

For 20 m² at 5 cm, the base volume is 1,000 L: 20 bags of 50 L. Half the depth needs 500 L; double needs 2,000 L.

27 ft³ = 1 yd³. One cubic foot is 28.316846592 L, and 1 m³ is 1,000 L. Use cubic yards or cubic meters when discussing bulk delivery.

Before you order.

Should I order bags or bulk mulch?

Compare the purchase volume with your supplier’s bag sizes and bulk units. This tool calculates volume and whole bags, not prices, delivery minimums or material weight.

How deep should mulch be?

Choose a depth suitable for your material and planting situation using supplier or local gardening guidance. The comparison table only shows how changing your input affects volume.

Does it account for settling or compaction?

No extra is included automatically. Add your own allowance, up to 30%, if appropriate. Actual coverage depends on the material and how it is spread.

Can I use it to fill a raised bed?

For inside bed dimensions and a soil layer to fill, use the Raised Bed Soil Calculator. This mulch tool is designed for combining surface areas under one common depth.

Method & privacy

For flat areas with a uniform layer. Inputs stay in this browser; measurements are not stored or sent to our servers. Results use full precision, with at most three decimals displayed. Positive values below 0.001 show <0.001. Whole-bag rounding uses a tiny tolerance for floating-point noise. Check your measurements before buying.