Raised-Bed Soil Calculator
Find exactly how much soil your raised beds need. Enter the size, pick a soil mix, and get total volume in cubic feet and cubic yards, a component-by-component mix recipe, and a bags-vs-bulk cost comparison — with tables and a downloadable PDF report.
| Component | Share | Cu ft | Bags |
|---|---|---|---|
| Enter a bed size to see the recipe | |||
| Option | Quantity | Cost | Note |
|---|---|---|---|
| Enter a bed size to compare | |||
How to use the raised-bed soil calculator
Four quick steps turn your bed size into total soil volume, a component-by-component mix recipe, and a bags-vs-bulk cost comparison — with tables and a downloadable report.
Enter bed dimensions
Give the inside length, width, fill depth, and how many identical beds. That sets the total volume.
Pick a soil mix
Choose Mel’s Mix, topsoil + compost, or a garden blend. Each splits the volume into its components.
Set buy & cost
Choose a bag size and enter your price per bag and per cubic yard for the bags-vs-bulk comparison.
Read results & save a PDF
Get cubic feet and yards, bags needed, the mix recipe, and the cheaper option — then download a report.
How the soil volume is calculated
Volume is length × width × depth; the mix recipe splits it by component share, and bags round up while bulk converts to cubic yards. Here is the exact math the calculator runs.
Worked example — one 8 × 4 ft bed, 12 in deep, Mel’s Mix, 1.5 cu ft bags at $8, bulk at $45/yd
Volume: 8 × 4 × (12 ÷ 12) = 32 cu ft = 32 / 27 ≈ 1.19 cu yd
Mel’s Mix: ⅓ each ≈ 10.7 cu ft of compost, coir, and vermiculite
Bags: ceil(32 / 1.5) = 22 bags → 22 × $8 = $176
Bulk: 1.19 × $45 ≈ $54
≈ 32 cu ft · 1.2 cu yd · bulk wins ($54 vs $176). Then add 5–10% extra.
Raised-bed soil charts
Handy lookups for soil volume by bed size, the mix recipes, and how many bags a cubic yard replaces. These are planning figures — order a little extra for settling.
| Bed size | Cubic feet | Cubic yards | 1.5 cu ft bags |
|---|---|---|---|
| 4 × 4 ft | 16 cu ft | 0.59 cu yd | 11 bags |
| 4 × 8 ft | 32 cu ft | 1.19 cu yd | 22 bags |
| 4 × 10 ft | 40 cu ft | 1.48 cu yd | 27 bags |
| 4 × 12 ft | 48 cu ft | 1.78 cu yd | 32 bags |
| 5 × 10 ft | 50 cu ft | 1.85 cu yd | 34 bags |
At 12 in fill. Halve the cubic feet for a 6 in bed; a 4 in bed is a third. Bags rounded up.
| Mix | Recipe | Best for |
|---|---|---|
| Mel’s Mix | ⅓ compost, ⅓ peat/coir, ⅓ vermiculite | Best quality, priciest |
| Topsoil + compost | ~60% topsoil, 40% compost | Budget-friendly |
| Garden blend | ~50% topsoil, 30% compost, 20% aeration | Balanced middle ground |
All three lean on compost for fertility. The calculator breaks each into per-component cubic feet.
| Bag size | Bags = 1 cu yd | Rough note |
|---|---|---|
| 1.0 cu ft | 27 bags | Small, heavy to haul |
| 1.5 cu ft | 18 bags | Most common |
| 2.0 cu ft | ~14 bags | Fewer trips |
Once you’re buying more than roughly a cubic yard, bulk delivery usually beats bags on price.
Everything the calculator works out
A bed size and a mix give you the volume, the recipe, and the cheaper way to buy — everything you need before a trip to the garden center.
Key figures behind the fill
Built for filling beds right
From a first square-foot garden to a whole row of beds, the same calculator turns dimensions into volume, a recipe, and the cheaper way to buy.
Just built a bed and needs to know how much soil to buy and what mix to use.
- Enter length, width & depth
- Pick Mel’s Mix or a blend
- Buy the bags, plus a little extra
Filling several beds and wants the cheapest way to source the soil.
- Set beds & bag size
- Enter bag & bulk prices
- Follow the cheaper option
Blending their own soil and needs the exact volume of each ingredient.
- Choose the recipe
- Read per-component cu ft
- Source each ingredient
7 tips for filling raised beds
Getting the volume right saves trips and money; getting the mix right grows a better garden. These points cover both.
Raised-bed soil calculator FAQ
The volume, mix, and buying questions people ask most when filling raised beds.
Multiply length × width × fill depth, keeping everything in feet: L × W × (depth ÷ 12) gives cubic feet.
Example: an 8 × 4 ft bed 12 in deep is 8 × 4 × 1 = 32 cu ft, or about 1.2 cubic yards. For several identical beds, multiply by the count.
Bagged soil settles and beds compact over the first season, so order about 5–10% extra and plan to top off next year.
Divide total cubic feet by the bag size and round up. Bags come in 1.0, 1.5, or 2.0 cu ft.
For 32 cu ft in 1.5 cu ft bags: 32 ÷ 1.5 = 21.3 → 22 bags. Larger 2.0 cu ft bags would need 16.
Since you round up and bags settle, add a cushion — and for anything above roughly a cubic yard, price out bulk delivery, which is usually much cheaper.
A cubic yard is 27 cubic feet (3 × 3 × 3 ft). So a 32 cu ft bed is 32 ÷ 27 ≈ 1.2 cu yd.
Bulk soil is sold by the cubic yard and bags by the cubic foot, so converting between them is how you compare prices. One cubic yard is roughly eighteen 1.5 cu ft bags.
Knowing the conversion is what reveals the bags-versus-bulk break-even for your project.
For small beds, bags are convenient and often fine; for large beds, bulk is usually far cheaper per cubic foot.
Bags cost more per unit but let you buy exactly what you need with no delivery fee. Bulk is sold by the cubic yard at a much lower rate but adds a delivery charge, so it wins once the volume savings outweigh that fee — often around a cubic yard or more.
This calculator prices both ways and flags the cheaper option for your project.
A good mix is light, drains well, and holds nutrients. Three common recipes cover most needs.
Mel’s Mix is equal parts compost, peat/coir, and coarse vermiculite — excellent but priciest. A budget mix is ~60% topsoil to 40% compost. A garden blend sits between, ~50% topsoil, 30% compost, 20% aeration.
All three lean on compost for fertility. Whichever you pick, the calculator breaks it into per-component volumes.
Most vegetables and flowers do well in 8–12 inches of good soil — room for roots without filling a very deep box entirely with expensive mix.
Root crops and deep feeders like tomatoes appreciate closer to 12 inches or more. If the bed sits on open ground, roots can also reach the soil below.
For a tall bed, the bottom can hold cheaper filler like logs or leaves — enter only the soil depth here.
Yes. Filling the lower portion of a tall bed with cheaper, bulky material saves soil and improves drainage — often called hügelkultur when logs are used.
Logs, branches, twigs, and leaves work well and slowly break down into organic matter; some people fill the bottom third to half of a deep bed this way. Keep the top 8–12 inches as quality mix where roots live.
In this calculator, enter only the soil depth you’ll actually fill, not the full box height.
Plan for about 5–10% more than the exact calculated volume. Bagged soil is compressed and fluffs up less than the label suggests once settling is accounted for, and fresh beds compact noticeably over the first watering and season.
A little extra means you won’t come up short mid-project, and leftovers top off containers or low spots. Expect to add more next year regardless — beds sink as organic matter breaks down.
So treat the estimate as a starting point: round up and keep a bag or two in reserve.
Estimate only — buy a little extra. Figures use US units (cubic feet, cubic yards, USD). Bagged soil is compressed and settles, and raised beds compact over the first watering and growing season, so order about 5–10% more than the exact volume and plan to top off next year as organic matter breaks down. Bulk delivery is usually far cheaper than bags for large beds but adds a delivery fee not included here. Prices vary by region and supplier — enter your own to compare. For planning purposes only.