Mulch and soil calculator
Plan material for one or more garden beds using your chosen depth. Compare whole bags with bulk volume and optional prices.
Your material estimate
Use the volume printed on the actual product bag. A weight-only label cannot determine volume without product-specific density.
How much mulch or soil do I need?
- Split the site into non-overlapping rectangles, circles or areas you have already measured.
- Choose a depth for each bed. The example depth is arithmetic only, not a recommendation for your plants or material.
- Add an optional allowance for uneven ground or settling, then use your supplier’s actual bag volume.
- Compare whole-bag material cost with bulk material cost. Delivery is shown separately; ask suppliers about minimum quantities, rounding and taxes.
The volume method
Rectangle area = length × width. Circle area = π × (diameter ÷ 2)². Multiply each area by its depth in the same length unit, then add the bed volumes. Allowance multiplies the total by 1 + percentage ÷ 100.
There are 12 inches in a foot, 27 cubic feet in a cubic yard and 1,000 liters in a cubic meter. One foot is exactly 0.3048 meters. Bags are rounded up after combining the beds.
Worked examples
A 10 × 10 ft bed at 3 inches: 100 × 3 ÷ 12 = 25 ft³ = 0.925926 yd³. With 2 ft³ bags and no allowance, buy 13 bags. At 5 per bag, material costs 65.
A 4 × 2 m bed at 5 cm: 8 × 0.05 = 0.4 m³ = 400 L. A 10% allowance makes 440 L, or 11 bags of 40 L. At 60 per m³, bulk material costs 26.40; a delivery charge of 20 makes 46.40 before tax.
A circular bed 6 ft across at 2 inches: π × 3² × (2 ÷ 12) = 4.712389 ft³. With 2 ft³ bags and no allowance, buy 3 bags.
Before you order
This is a geometric volume estimate, not a planting-depth recommendation. Settling, compaction, existing material and uneven ground can change how much you need. Follow product and plant-specific guidance. It does not convert volume to weight or tonnes and does not provide structural advice.
Costs use only the prices you enter; no live supplier prices or currency conversion are used. Bulk material is priced at the calculated volume without supplier minimums or ordering increments. All inputs stay in your browser.
Sources and assumptions
Iowa State University Extension: determining mulch quantities