Mulch Calculator
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Enter your garden bed dimensions and depth to find out how many bags or cubic yards of mulch to buy.
1. Measure your area
2. Choose depth
2–3" for existing beds · 3–4" for new beds · 1–2" for top-dress
3. Adjust & price (optional)
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How to measure your space
- 1. Rectangle beds: Walk the length and width with a tape measure. Record in feet and inches.
- 2. Curved or odd-shaped beds: Break the area into rough rectangles, measure each, and use the "Irregular" shape option to add them together.
- 3. Depth: Use a ruler to check existing mulch depth. For a new bed, 2–3" is standard; for heavy weed suppression, use 3–4".
- 4. Subtract obstacles: Deduct space taken by large plants, stones, or hardscape — or just leave the small ones in and let the 5% waste factor cover it.
Frequently Asked Questions
How many bags of mulch do I need for 100 square feet?
At 3 inches deep, 100 sq ft needs 0.93 cubic yards — about 13 bags of 2 cu ft mulch. Round up to 14. At 2 inches: 9 bags. The Mulch Calculator computes this instantly for any size.
How deep should I apply mulch?
Apply 2–3 inches for existing beds, 3–4 inches for new beds or heavy weed suppression. Never pile mulch more than 4 inches deep or against plant stems.
How many bags of mulch are in a cubic yard?
There are 13.5 standard 2-cubic-foot bags in one cubic yard. If you need more than 2–3 yards, bulk delivery is usually cheaper than buying bags.
How much does a cubic yard of mulch cover?
At 3 inches deep, 1 cubic yard covers 108 sq ft. At 2 inches: 162 sq ft. At 1 inch: 324 sq ft.
Formula: Volume (cu ft) = Area (sq ft) × Depth (in) ÷ 12. Bags = Volume (cu yd) × 13.5, rounded up. See our methodology page for all constants and sources.