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
Square Foot Garden Spacing Calculator
Estimate square-foot grid count and plant counts for common raised bed crops.
Preset: square-foot planting layout
Formula: total squares = floor(length ft) × floor(width ft)
Worked example: A 4×8 bed gives 32 one-square-foot spaces. A 4×4 bed gives 16 spaces.
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 grid counts as a yield guarantee.
- Ignoring mature plant size and trellis layout.
- Skipping the seed packet or local guidance.
Page-specific notes
- Plant counts are general spacing estimates.
- Large crops may need more room.
Planning assumptions and sources
Spacing pages use square-foot grid math plus crop-specific assumptions; always verify seed packet spacing and mature plant size.
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 Illinois Extension: Square Foot Gardening A: Square-foot gardening uses compact raised beds divided into 1-ft² sections; plant for mature size and avoid bed compaction.
- University of Maryland Extension: Growing Tomatoes in a Home Garden A: Tomato spacing depends on growth habit and support; supports conservative square-foot tomato warnings.
- University of Minnesota Extension: Growing carrots and parsnips A: Carrots need direct seeding, thinning room, moisture, and loose depth; root quality is variety and soil dependent.
- University of Maryland Extension: Growing Carrots in a Home Garden A: Carrot varieties differ in root length; dense wide-row planting still requires thinning and variety awareness.
- University of Minnesota Extension: Starting seeds indoors A: Seed depth should follow package directions; fallback rules are only general guidance.
- University of Maryland Extension: Container seed spacing reminder A: For containers and raised-bed planning, follow seed packet spacing, depth, and timing for the crop.
- USDA National Agricultural Library: Raised Beds & Container Gardening A: Trust hub for raised beds, containers, growing media, water, light, and related resources.
- University of Minnesota Extension: Raised bed gardens A: Raised bed placement, water access, sunlight, access, fill, and soil-mix considerations.
- 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.
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.