Formula
How the mulch estimate works
- Mulch volume = bed length × bed width × mulch depth
- Adjusted volume = mulch volume × (1 + extra allowance %)
- Full bags = adjusted volume ÷ volume per bag, rounded up
Free project planning tool
Mulch calculator
Find mulch volume, full bag quantity, bulk order volume, and estimated bag or bulk material cost.
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Example calculation
A 20 × 8 ft garden bed at 3 in deep needs 40 cubic feet before extra allowance. With 5% extra and 2 cubic foot bags, the purchase quantity is 21 bags, or about 1.56 cubic yards.
Planning tips
- Measure irregular beds as several rectangles and add their results.
- Use the bag volume printed on the product, not the bag’s outside dimensions.
- Avoid piling mulch against trunks, stems, siding, or drainage openings.
Common questions
Mulch calculator FAQ
How deep should mulch be?
A 2–3 inch layer is a common planning range for many landscape beds, but plant type, existing mulch, drainage, and local conditions should guide the depth.
How many bags are in one cubic yard?
One cubic yard is 27 cubic feet, so it equals about fourteen 2-cubic-foot bags or nine 3-cubic-foot bags after rounding up.
Should I add extra mulch?
A small allowance can cover uneven beds, settlement, and measurement error. Avoid excessive depth around plants and structures.