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
4×8 Raised Bed Soil Calculator
Use 4×8 presets for 6, 8, 10, 12, 18, and 24 inch raised bed depths.
Preset: raised bed dimensions
Formula: 4 × 8 × depth in feet = cubic feet of soil
Worked example: A 4×8×12 in bed is 32 ft³. With 10% settling, it becomes 35.2 ft³.
Adjust the live inputs above before copying the shopping list, printing the result, or buying material.
4×8 depth comparison
These rows use one 4×8 bed, 0 in freeboard, 10% settling allowance, and 2 ft³ bags. Change the live calculator for other assumptions.
| Depth | Before settling | With 10% | 2 ft³ bags | Planning note |
|---|---|---|---|---|
| 6 in | 16.00 ft³ | 17.60 ft³ / 0.65 yd³ | 9 | Shallow planning depth: better for greens, herbs, and short-root crops than for large fruiting crops. |
| 8 in | 21.33 ft³ | 23.47 ft³ / 0.87 yd³ | 12 | Moderate shallow depth: workable for many smaller crops, but limited for deep-rooted or long-season vegetables. |
| 10 in | 26.67 ft³ | 29.33 ft³ / 1.09 yd³ | 15 | Common raised-bed depth: a practical planning depth for many vegetables when soil and watering are managed well. |
| 12 in | 32.00 ft³ | 35.20 ft³ / 1.30 yd³ | 18 | Common raised-bed depth: a practical planning depth for many vegetables when soil and watering are managed well. |
| 18 in | 48.00 ft³ | 52.80 ft³ / 1.96 yd³ | 27 | Deeper bed: higher material cost, but more root volume and more flexibility for larger crops. |
| 24 in | 64.00 ft³ | 70.40 ft³ / 2.61 yd³ | 36 | Very deep bed: compare bulk delivery with bags and check whether full-depth premium mix is necessary. |
Quick copy: 6 in: 16 ft³ before settling; 17.6 ft³ with 10% settling; 0.65 yd³; about 9 × 2 ft³ bags. 8 in: 21.33 ft³ before settling; 23.47 ft³ with 10% settling; 0.87 yd³; about 12 × 2 ft³ bags. 10 in: 26.67 ft³ before settling; 29.33 ft³ with 10% settling; 1.09 yd³; about 15 × 2 ft³ bags. 12 in: 32 ft³ before settling; 35.2 ft³ with 10% settling; 1.3 yd³; about 18 × 2 ft³ bags. 18 in: 48 ft³ before settling; 52.8 ft³ with 10% settling; 1.96 yd³; about 27 × 2 ft³ bags. 24 in: 64 ft³ before settling; 70.4 ft³ with 10% settling; 2.61 yd³; about 36 × 2 ft³ bags.
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
- Measuring outside dimensions instead of inside fill dimensions.
- Forgetting freeboard below the bed rim.
- Buying bags without checking the package volume.
Page-specific notes
- 4×8 gives 32 square feet of planting area.
- 8×4 is the same volume.
Planning assumptions and sources
Raised-bed pages use deterministic volume math plus planning assumptions for settling, freeboard, bag labels, and local growing conditions.
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: 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.
- 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 Testing and Soil Testing Labs A: Soil tests provide pH, nutrient, organic-matter, and recommendation context; vegetable gardens should consider lead testing.
- NIST: Approximate Conversions from U.S. Customary Measures to Metric A: Source provenance for U.S. customary and metric unit conversion factors.
- University of Maryland Extension: Understanding Your Soil Test Report A: Soil reports show pH, phosphorus, potassium, magnesium, calcium, organic matter, and lab recommendations; calculators should not replace lab interpretation.
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.