Skip to content
CalcWolf › DIY › Mulch Calculator
DIY

How Much Mulch Do You Need?

Calculate cubic yards and bags of mulch for garden beds. Enter bed dimensions and desired depth for exact quantities.

📅 Updated April 2026 ✅ Formula verified 📖 4 min read 🆓 Free · No sign-up

Mulch Coverage Formula

Cubic yards = (Length × Width × Depth in inches ÷ 12) ÷ 27. A 20×6 foot bed at 3 inches deep: (20 × 6 × 0.25) ÷ 27 = 1.1 cubic yards. For multiple beds, calculate each and add together. One cubic yard covers approximately 108 sq ft at 3 inches deep or 162 sq ft at 2 inches. Standard recommendation: 2-3 inches for most garden beds, 3-4 inches for weed suppression.

Bulk vs Bags

Bulk delivery: $25-45 per cubic yard + $40-80 delivery fee. Best for 3+ cubic yards. Bags (2 cu ft): $3.50-6 each. You need 13.5 bags per cubic yard. For 3 cubic yards, that is 40+ bags at $140-240. Break-even: Bulk delivery usually saves money starting at 3-4 cubic yards. Below that, bags are more practical (no delivery fee, easier to store, less waste).

⚡ CalcWolf Insight

Mulch calculator searches spike March-May as homeowners start spring landscaping. The audience has immediate purchase intent — they need mulch this weekend. Garden center and landscaping supply advertisers pay $3-8 CPC for these searches.

Frequently asked questions
How deep should mulch be?▾
2-3 inches for most garden beds and around trees. 3-4 inches for weed suppression in pathways. Never exceed 4 inches — too much mulch suffocates roots and creates pest habitat. Keep mulch 3-6 inches away from tree trunks and plant stems to prevent rot (no "mulch volcanoes").
How often should I replace mulch?▾
Organic mulch (hardwood, pine bark) decomposes and should be replenished annually — add 1-2 inches on top of existing mulch. Cedar lasts 2-3 years. Rubber mulch lasts 10+ years but does not improve soil. Pine straw needs refreshing every 6-12 months. If mulch looks thin or you can see bare soil, it is time to add more.
✓ Math logic verified against primary sources → See our verification process
Kevin Glover
Founder, CalcWolf · GLVTS · Blickr
All formulas sourced from primary references — IRS publications, peer-reviewed research, and official standards. Results are tested against independent reference calculators before publishing. Rates and brackets updated when official sources change. Editorial policy →

Embed This Calculator

Add this calculator to your blog or website. Copy the code below and paste it into your HTML.

<iframe src="https://calcwolf.com/embed/mulch-coverage-calculator/" width="100%" height="420" style="border:1px solid #e5e7eb;border-radius:12px;" frameborder="0" loading="lazy" title="Mulch Calculator"></iframe>
Size:

Free to use. The embed includes a small "Powered by CalcWolf" link. By embedding, you agree to keep this attribution visible.

🐛 Report a Calculator Error
Found a bug or outdated data? Reports go directly to Kevin and are reviewed personally.