Raised Bed Soil Calculator
Calculate exactly how much soil, compost, and amendments you need for your raised garden bed.
Pick a preset or enter custom dimensions below
Most vegetables need at least 6–12 inches of soil
60% topsoil, 40% compost. Great all-purpose mix.
You Need
Soil Mix Breakdown
Bed area: 32.0 sq ft · Perimeter: 24.0 ft
Common questions
The amount of soil depends on your bed dimensions. Multiply length x width x depth (all in feet) to get cubic feet. For example, a 4x8-foot bed that is 12 inches deep needs 32 cubic feet of soil. Divide by 27 to convert to cubic yards if ordering in bulk. Our calculator above handles all the math for you, including multiple bed shapes and soil mix breakdowns.
How This Calculator Works
This calculator computes soil volume using standard geometric formulas: length × width × height for rectangular beds, π × r² × height for circular beds, and a 75% area factor for L-shaped beds. Weight estimates use an average of 40 lbs per cubic foot of garden soil mix. Cost estimates are based on typical retail pricing: topsoil at $0.75/cu ft, compost at $1.50/cu ft, and peat moss/vermiculite at $2.00-$3.50/cu ft. Bulk delivery (by the cubic yard) is usually 30-50% cheaper than bagged soil for beds larger than 4×8 feet.
Tips for Filling Raised Beds
- For beds deeper than 12 inches, fill the bottom third with logs, sticks, or leaves (hugelkultur method) to reduce soil cost and improve drainage.
- A 60/40 topsoil-to-compost ratio works for most vegetables. Mel's Mix (⅓ compost, ⅓ peat, ⅓ vermiculite) is popular for square-foot gardening but costs 2-3x more.
- Soil settles 10-15% in the first season. Consider overfilling slightly and topping off with compost each spring.
- Once your bed is filled, use our planting date calculator to find the best time to plant in your zone, then check seed spacing to maximize your harvest.
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Quick answer▾
A standard 4×8 foot raised bed that's 12 inches deep needs about 32 cubic feet of soil. Roughly 1.2 cubic yards or 16 bags of 2-cubic-foot bagged soil. The ideal mix is 60% topsoil and 40% compost, costing approximately $40-80 depending on your source.
Data last updated: March 2026