Mulch Calculator

A 10 × 10 ft bed at 3 inches deep needs 25 cubic feet of mulch — about 0.93 cubic yards or 13 bags of 2 cubic feet each (with 10% extra). For 2 inch depth the same bed needs roughly 8–9 bags.

Two to three inches is ideal for most beds. That is enough to suppress weeds and hold moisture without smothering plant roots. Never pile mulch against trunks or stems ("mulch volcano") — keep 2–3 in of clearance. Top up to 3 in every spring as the existing layer breaks down.

A cubic yard is 27 cubic feet. The standard 2 cu ft bag takes 13.5 bags to equal 1 cubic yard. A 3 cu ft bag takes 9 bags. Bulk mulch (ordered by the cubic yard) is almost always cheaper once you need more than about 10–12 bags.

Use bags for small beds (under 2–3 cubic yards). For larger jobs, bulk mulch delivered by the yard is significantly cheaper and saves multiple trips to the store. The break-even is typically around 10–12 bags, though it varies by supplier.

In planting beds, fabric often does more harm than good long-term — it prevents natural soil improvement and can become a weed trap as it breaks down. A thick layer of mulch (3 in) suppresses weeds effectively on its own. Fabric works better under gravel or rock paths where you do not want the soil to mix.

Three inches of wood chip or shredded bark mulch blocks most weed germination. Research shows that at 3 in, weed emergence drops by over 90%. Four inches is even better, but beyond 4 in mulch can compact, reduce aeration, and hold too much moisture near plant stems.

Multiply the area in square feet by the depth in feet, then divide by 27. For example: 200 sq ft × (3 in ÷ 12 in/ft) ÷ 27 = 200 × 0.25 ÷ 27 = 1.85 cu yd. Or just enter your beds and depth above — the calculator does this automatically.