Free Mulch Calculator

🌿 FREE GARDEN TOOL

Mulch Calculator

Find out how much mulch you need for beds, borders and paths — in cubic feet, cubic yards, bags and litres — plus an estimated cost, so you order the right amount first time.

✓ Free & instant   ✓ Imperial & metric   ✓ No sign-up needed

🧮 Mulch Calculator

Please enter a length, width and depth greater than zero.

Your Results

Mulch volume—
Cubic yards—
Bulk mulch is sold by the cubic yard — 1 cubic yard = 27 cubic feet.
Bags needed—
Estimated cost—
Based on the price per cubic yard you entered.
Your mulched area preview will appear here

How to Calculate Mulch

Use the same volume formula as soil: Length × Width × Depth = Volume. For a rectangular bed, multiply length by width to get the area, then multiply by depth in feet (inches ÷ 12). Divide cubic feet by 27 for cubic yards.

Worked example: a 20 ft × 10 ft bed at 3 inches deep: 20 × 10 × 0.25 ft = 50 cubic feet, or 1.85 cubic yards. With 10% extra, order 55 cubic feet (2.04 cubic yards) — about 28 bags of 2 cu ft mulch, costing about $91.67 at $45 per cubic yard.

Where you mulchRecommended depthWhy
Flower beds & borders2–3 in (5–8 cm)Suppresses weeds, keeps moisture in
Vegetable beds2–3 in (5–8 cm)Keeps soil cool and moist
Around shrubs & trees3–4 in (8–10 cm)Deeper cover for larger root zones
Garden paths3–4 in (8–10 cm)Stands up to foot traffic

Common Mistakes to Avoid

  • Mulching too deep — more than 4 inches can suffocate roots and hold too much moisture against stems.
  • Piling mulch against trunks — the classic “mulch volcano” causes rot. Keep mulch 3–6 inches away from trunks and stems.
  • Using fresh wood chips on vegetable beds — fresh chips can temporarily tie up nitrogen. Compost them first or use straw, leaves or bark.
  • Measuring a round bed as a square — for round beds, use π × radius² for the area, or measure in sections.
💡 Pro tip: Mulch in spring after the soil has warmed, and top up in autumn. A 2–3 inch layer typically needs refreshing once a year as it breaks down.

Frequently Asked Questions

At 3 inches deep, a 10×10 ft area (100 sq ft) needs 25 cubic feet — 0.93 cubic yards, or 13 bags of 2 cu ft mulch. Add 10% extra for settling.
One cubic yard equals 27 cubic feet — about 14 bags of 2 cu ft, or 9 bags of 3 cu ft mulch.
2–3 inches is right for most beds. Go to 4 inches around trees and shrubs, and never exceed 4 inches anywhere.
Usually yes, once you need a cubic yard or more. Bags are convenient for small areas, but bulk delivery costs far less per cubic foot.
It is optional. Fabric blocks weeds but also blocks worms and makes it harder for mulch to break down into the soil. Thick mulch alone usually does the job.

Related Garden Tools

Finish the job with the Raised Bed Soil Calculator, Compost Estimator and Vegetable Plant Spacing Calculator. See all tools on the Free Tools page.