Interactive raised bed calculator
Enter bed size. Get soil volume, bags, cost, and a shopping list.
Default example: one 4×8×12 in bed, 10% settling, and 2 ft³ bags. Results update automatically as inputs change.
More planners: mix, containers, spacing, top-off, depth, cost, multi-bed, shapes
Raised Bed Soil & Planting Calculator
Raised Bed Soil Mix Calculator
Split total raised bed soil volume into topsoil, compost, potting mix, soilless mix, or Mel’s Mix style components.
Preset: soil mix component split
Formula: component volume = total volume × component percentage
Worked example: A 32 ft³ 60/30/10 mix needs 19.2 ft³ topsoil, 9.6 ft³ compost, and 3.2 ft³ potting mix.
Adjust the live inputs above before copying the shopping list, printing the result, or buying material.
How to use this calculator
- Confirm the preset and unit labels.
- Replace every default that differs from your bed, container, bag, price, or planting plan.
- Review volume, bag count, cost, warnings, and rounding.
- Check package labels and local conditions before purchasing or planting.
What to verify
- Treating a ratio calculator as a universal soil recipe.
- Entering custom percentages that do not total 100%.
- Skipping soil-test and drainage considerations.
Page-specific notes
- This calculates ratios; it does not prescribe a regional soil recipe.
- Custom percentages must total 100%.
Planning assumptions and sources
Mix pages split volume by ratio; they do not prescribe a universal soil recipe for every region.
BedSoil keeps deterministic volume math separate from gardening assumptions. Cubic-foot, cubic-yard, liter, quart, gallon, and bag-count calculations come from your inputs; crop spacing, crop depth, mix ratio, and container advice are planning aids that need product labels, seed packets, local Extension guidance, and soil-test context.
- University of Maryland Extension: Soil to Fill Raised Beds A: Raised bed fill scenarios, hard-surface depth guidance, topsoil limits, soil testing, and lead caution.
- University of Maryland Extension: Growing Vegetables in Raised Beds A: Raised bed preparation, compost/topsoil mixes, minimum media depth, and bed-management guidance.
- Oregon State Extension: How to use compost in gardens and landscapes A: Compost bag sizes, bulk cubic yards, 27 ft³ per yd³, and annual compost planning ranges.
- University of Maryland Extension: Organic Matter and Soil Amendments A: Organic matter benefits and cautions; volume ratios are planning estimates, not lab measurements.
- Square Foot Gardening Foundation: Mel's Mix Resources B: Mel's Mix source for equal-volume style estimates; use as a method label, not a universal Extension prescription.
- University of Minnesota Extension: Too much compost and manure A: Too much compost or manure can create nutrient and salt issues; compost-heavy mixes need caution.
- University of Minnesota Extension: Coffee grounds, eggshells and Epsom salts A: Do not recommend Epsom salts or eggshells as default fixes; soil-test context matters.
- Oregon State Extension: Cubic yard compost reference A: Direct support for 1 yd³ = 27 ft³ bulk-compost and bulk-soil planning.
- Oregon State Extension: Raised bed gardening A: Raised beds often require substantial soil or organic material, making local availability, bulk mixes, and cost comparisons important.
Source library coverage
The project source library now contains 39 curated references. This page shows the sources most relevant to the active calculator mode; 30 additional references cover SERP patterns, containers, compost, soil testing, amendments, and related crop assumptions.
Always check product labels, seed packets, local extension guidance, soil tests, delivery minimums, drainage, and site conditions before purchasing materials or planting.
FAQ
How much soil do I need for a 4x8 raised bed?
A 4×8 bed filled 12 inches deep needs 32 cubic feet, or about 1.19 cubic yards, before any settling allowance.
How many bags of soil do I need for a raised bed?
Divide the required cubic feet by the bag volume in cubic feet, then round up. The calculator does this automatically.
Should I add extra soil for settling?
Many gardeners add 10–15% for initial settling, especially when compost-heavy material is used.
What is the difference between cubic feet and cubic yards?
One cubic yard is 27 cubic feet. Bulk soil is usually sold by the cubic yard; bags are often labeled in cubic feet, dry quarts, or liters.
Is 40 lb of soil the same as 40 quarts?
No. Pounds measure weight, while quarts measure volume. Soil weight changes with moisture and material density.
How deep should a raised bed be?
Six to eight inches can work for shallow greens and herbs. Tomatoes, peppers, squash, and longer root crops usually benefit from 12 inches or more.
Disclaimer
BedSoil results are planning estimates for buying and mixing soil. They are not agricultural, engineering, pest, disease, fertilizer, or crop-yield advice. Check product labels, local material quality, drainage, bed construction, climate, and crop variety before purchasing materials.