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Mulch Calculator Guide
Mulch keeps moisture in, weeds down, and beds looking finished — but only at the right depth. This calculator converts your bed size and depth into cubic yards and the number of bags, plus an optional cost estimate.
Cubic yards = (area × depth in feet) ÷ 27. Bags = total cubic feet ÷ bag size (most bags are 2 cubic feet). One cubic yard covers about 108 sq ft at 3 inches deep.
How Much Mulch Do I Need?
Multiply the bed length by width for the area, multiply by the depth in feet for cubic feet, then divide by 27 for cubic yards. A 2–3 inch layer is right for most beds; go 3–4 inches where you want stronger weed suppression.
Mulch Coverage Reference
| Depth | Coverage per cubic yard | Coverage per 2 ft³ bag |
|---|---|---|
| 2 inches | ~162 sq ft | ~12 sq ft |
| 3 inches | ~108 sq ft | ~8 sq ft |
| 4 inches | ~81 sq ft | ~6 sq ft |
Worked Example
For a 20 ft × 10 ft bed at 3 inches: area = 200 sq ft; volume = 200 × (3÷12) = 50 cubic feet; cubic yards = 50 ÷ 27 = 1.85 yd³; bags = 50 ÷ 2 = 25 bags.
Tips
- Buy in bulk past ~1 cubic yard — bulk delivery is much cheaper than bags for big beds.
- Don't pile mulch against stems or trunks; keep a small gap to prevent rot.
- Refresh, don't rebury: top up 1 inch a year rather than adding a full layer each season.
Finishing a lawn and beds? See our Grass Seed Calculator and Fertilizer Calculator.
Frequently Asked Questions
How much mulch do I need?
Multiply bed area by depth in feet, divide by 27 for cubic yards, or divide the cubic feet by 2 for the number of standard bags.
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so it equals about 13.5 bags of 2-cubic-foot mulch.
How deep should mulch be?
2 to 3 inches suits most beds, with 3 to 4 inches where you want stronger weed control.
How much area does a bag of mulch cover?
A 2-cubic-foot bag covers about 12 square feet at 2 inches deep or 8 square feet at 3 inches.
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