BuildCalc Pro

Mulch & Soil Calculator

Calculate cubic yards of mulch, soil, compost, gravel, or sand needed for garden beds and landscaping.

Written & reviewed by Michael FairUpdated June 2026Based on U.S. codes & pricingHow we calculate

How Much Mulch or Soil Do You Need? A Complete Guide

Landscaping with mulch, soil, or compost is one of the simplest ways to improve your yard's appearance and plant health. The challenge is buying the right amount — landscaping materials are sold by cubic yards, but most homeowners think in terms of area and depth.

The formula is straightforward: multiply length × width × depth (all in feet), then divide by 27 to convert cubic feet to cubic yards. For circular beds, use the formula: π × radius² × depth ÷ 27. Our calculator handles both rectangular and circular shapes automatically.

Recommended mulch depth is 2-4 inches for most applications. Use 2-3 inches around plants and flower beds, and 3-4 inches for weed suppression in open areas. Avoid piling mulch deeper than 4 inches, as this can suffocate plant roots and trap excessive moisture.

Material weight varies significantly. Mulch weighs about 400-800 pounds per cubic yard. Topsoil weighs approximately 2,000 pounds per cubic yard. Gravel can weigh 2,500-3,000 pounds per cubic yard. These weights affect delivery costs and whether you need a truck or trailer.

Buying in bulk (by the cubic yard) is much cheaper than buying bags. Bagged mulch costs roughly $4-$7 per 2 cubic foot bag, which translates to $54-$95 per cubic yard. Bulk mulch delivered costs $25-$50 per cubic yard — roughly half the bagged price.

How to Use This Calculator

1. Select Imperial or Metric. 2. Choose bed shape: rectangle or circle. 3. Enter dimensions and desired depth. 4. Select the material type for weight estimation. 5. Optionally enter cost per cubic yard. 6. Click "Calculate" for volume and bag estimates. Tip: 2-3 inches is standard mulch depth. For topsoil, 4-6 inches is typical for new beds.

Understanding Your Result

Your mulch/soil result is in cubic yards — the standard bulk-delivery unit. One cubic yard fills about 13.5 standard 2-cubic-foot bags. The calculator accounts for your chosen depth and a small settling allowance (mulch compresses 5–10% over the first few weeks as it absorbs moisture). Bulk delivery is almost always cheaper than bags: expect $25–$45 per cubic yard delivered for hardwood mulch vs. $4–$6 per 2 cu ft bag ($54–$81 per cubic yard equivalent).

Key Formulas

Mulch/Soil Volume

Length (ft) × Width (ft) × Depth (in) ÷ 324 = Cubic Yards

Multiply length and width in feet by depth in inches, then divide by 324 (27 × 12) to convert directly to cubic yards.

Circular Bed Volume

π × Radius² (ft) × Depth (in) ÷ 324 = Cubic Yards

For circular garden beds, use the radius (half the diameter) squared times π, times depth in inches, divided by 324.

Bags Needed (2 cu ft)

Cubic Yards × 13.5 = Number of 2 cu ft Bags

One cubic yard = 27 cubic feet. Divide by bag size: 27 ÷ 2 = 13.5 bags per cubic yard.

Worked Example

Hardwood Mulch for a 30 × 4-Foot Garden Bed

  1. 1Bed dimensions: 30 ft long × 4 ft wide, mulch depth = 3 inches.
  2. 2Convert depth to feet: 3 ÷ 12 = 0.25 ft.
  3. 3Volume in cubic feet: 30 × 4 × 0.25 = 30 cu ft.
  4. 4Convert to cubic yards: 30 ÷ 27 = 1.11 cu yd.
  5. 5Add 5% settling allowance: 1.11 × 1.05 = 1.17 cu yd → round to 1.25 cu yd.
  6. 6Bag option: 1.25 × 27 ÷ 2 = 16.9 → 17 bags (2 cu ft each) at $4–$6 = $68–$102.
  7. 7Bulk option: 1.25 cu yd × $25–$45/yd = $31–$56 + delivery ($0–$75 with minimum order).

1.25 cubic yards — roughly 17 bags ($68–$102) or a small bulk load ($31–$131 with delivery). Bulk saves 40–60% on material cost.

Assumptions Behind This Estimate

  • Volume formula: length (ft) × width (ft) × depth (ft) ÷ 27 = cubic yards.
  • Recommended depths: 2–3 inches for mulch (weed suppression), 4–6 inches for playground mulch (fall protection), 6–12 inches for soil in raised beds.
  • A 5% settling allowance is used for mulch; soil and compost typically settle 10–15% and may need a higher factor.
  • One cubic yard of mulch weighs 400–800 lbs depending on type and moisture; soil/compost weighs 1,000–1,400 lbs per cubic yard.
  • Pricing assumes standard hardwood mulch. Dyed mulch costs 20–40% more; cedar and cypress run 50–100% more than hardwood.

Before You Buy: Practical Advice

  • Never pile mulch against tree trunks or plant stems ("volcano mulching") — it traps moisture and causes bark rot. Leave a 3–4 inch gap around the base.
  • For weed suppression, 3 inches is the minimum effective depth. Anything less and weeds push through within weeks.
  • Bulk mulch is cheapest, but confirm your supplier's minimum order — many require 2–3 cu yd minimum for delivery. Below that, bags may be more practical.
  • Top up mulch annually. Hardwood mulch decomposes about 1 inch per year, so a 3-inch bed needs roughly 1 inch of fresh mulch each spring.
  • For vegetable gardens, avoid dyed mulch — the dyes are usually safe but can contain recycled wood with contaminants. Use natural hardwood or straw instead.

Frequently Asked Questions

How many cubic yards of mulch for 1000 sq ft?

For 1,000 square feet at 3 inches deep, you need approximately 9.3 cubic yards of mulch. At 2 inches deep, you need about 6.2 cubic yards. Our calculator gives you the exact amount based on your specific depth.

How many bags of mulch equal a cubic yard?

One cubic yard equals 27 cubic feet. Standard mulch bags are 2 cubic feet, so you need 13.5 bags (round up to 14) to equal one cubic yard. Buying bulk delivery is usually cheaper for anything over 3 cubic yards.

What depth should mulch be applied?

Apply 2-3 inches of mulch around plants and in flower beds. Use 3-4 inches for weed suppression in open areas. Never exceed 4 inches as excessive mulch can damage plants by trapping moisture and preventing air circulation.

How much does a cubic yard of topsoil weigh?

A cubic yard of topsoil weighs approximately 1,800-2,200 pounds depending on moisture content. Wet soil can weigh significantly more. Make sure your vehicle or trailer can handle the weight before picking up bulk soil.