Compost Calculator — Cubic Yards, Bags & Cost

Free Landscape Calculator

Compost Calculator

Calculate exactly how many cubic yards or bags of compost for garden beds, lawns and raised planters. Instant results with bulk and bagged options plus cost estimates.

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Compost Calculator
Cubic yards and bags for garden beds
Dimensions
ft
ft
in
Common Depths
📐 Your Results
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Cubic Yards
Bulk order
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2cu-ft Bags
If bagged
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Cubic Feet
Volume
Estimated Cost
Avg. $30–$50/cubic yard
$—
💡 Always order 10–15% extra for waste and settling.

📊 Understanding Your Results

Cubic Yards — Standard unit for bulk compost. One cubic yard covers 162 sq ft at 2 inches deep or 108 sq ft at 3 inches deep.

2 cu-ft Bags — Standard retail bag. For projects over 2 cubic yards, bulk is 40–60% cheaper.

Cost Estimate — Based on average US bulk compost prices of $30–$50 per cubic yard.

How the Compost Calculator Works

Our compost calculator uses a volumetric formula to determine how much compost is needed based on your project area and application depth. Compost improves drainage in clay soils, increases water retention in sandy soils and feeds soil biology.

The Compost Formula

Step 1: Volume (cubic feet) = Length × Width × Depth (all in feet)
Step 2: Cubic Yards = Cubic Feet ÷ 27
Step 3: Bags (2 cu ft) = Cubic Feet ÷ 2 (round up)
Step 4: Add 10% for uneven surfaces and settling

Example: 20×10 ft garden bed at 3 inches = 200 × (3÷12) = 50 cu ft = 1.85 cubic yards = 25 bags. Bulk at $38/yard = $70 vs bags $150.

Compost Application Rates by Project

ApplicationDepth1 Cu Yd Covers
Lawn top-dressing0.5 inch648 sq ft
Existing garden beds2 inches162 sq ft
New garden beds3–4 inches81–108 sq ft
Raised bed fill4–6 inches54–81 sq ft

Frequently Asked Questions

Common questions about compost for garden beds and soil improvement.

How much compost per square foot?
At 2 inches deep: 1 cubic yard covers 162 sq ft. At 3 inches: 108 sq ft. At 1 inch: 324 sq ft. For 100 sq ft at 2 inches = 0.62 cubic yards = 8–9 bags.
What is the difference between compost and topsoil?
Compost is decomposed organic matter used as a soil amendment. Topsoil is used to fill and build soil depth. For best results combine both: use topsoil for bulk and amend with 20–30% compost.
How often should I add compost to my garden?
Apply once or twice per year. Spring before planting and fall after harvest are best times. Vegetable gardens benefit most from twice-yearly applications.
Can I use too much compost?
Yes — more than 4 inches can temporarily tie up nitrogen. The ideal is 1–2 inches annually to maintain 5–10% organic matter in soil.
How much does compost cost per cubic yard?
Bulk compost costs $25–$60 per cubic yard. Municipal compost: $20–$35/yard. Mushroom compost: $25–$45/yard. Many municipalities offer free or reduced-price compost — check your local waste management.

💡 Compost Tips

Apply in early spring for best growing season results.

Good compost smells earthy — not sour or ammonia-like.

Check your local municipality — many offer free compost.