Free Raised Bed Soil Calculator
A raised bed is a box, so its soil is area × depth — but people buy it as a blend, and a blend has to survive rounding. This tool sizes the soil for any number of beds, then splits it into topsoil, compost and perlite and rounds each component on its own.
Your estimate
3 beds need 88.0 cu ft (3.26 cu yd) of soil, including 10% overage.
| Component | Share | Needed | Buy | At your price |
|---|---|---|---|---|
| Topsoil | 60 % | 1.96 cu yd | 2.0 cu yd | $68.00 |
| Compost | 30 % | 0.98 cu yd | 1.0 cu yd | $42.00 |
| Perlite | 10 % | 0.33 cu yd (8.8 cu ft) | 5 × 2.0 cu ft bags | $90.00 |
| Total | 3.26 cu yd | 3.37 cu yd equivalent | $200.00 |
Buy-list total ≈ $200.00. Bought: 3.37 cu yd equivalent against 3.26 cu yd needed — rounding adds 0.11 cu yd.
- Includes 10% overage (8.00 cu ft) — our editable default, not a published standard.
- Each component is rounded up to its own sold increment, so the blend shares survive rounding.
- Depth and blend are your inputs. The presets are example starting points you can edit, not recommendations: this tool does not recommend a bed depth or a soil recipe, and it does not tell you what to grow.
Densities: topsoil uses REG-03b (2,200–2,600 lb/cu yd, working 2,300), compost uses REG-03c (800–1,500 lb/cu yd, working 1,000) — both secondary, primary unverified. Perlite is bought by the bag; no density is used.
Perlite bag REG-05: 2.0 cu ft. Prices are yours, not ours: the figures in the form are examples to start from. The answer says what your order costs at the price you typed.
Buy-list — materials list
| Depth | 10.00 in |
|---|---|
| Beds | 3 |
| Overage | 10.0 % |
| Blend | 60 / 30 / 10 % |
| Prices | $34.00/cu yd topsoil · $42.00/cu yd compost · $18.00/bag perlite |
| Region | United States (US customary, cu yd increment) |
| Item | Quantity | At your price |
|---|---|---|
| Topsoil 60% | 2.0 cu yd | $68.00 |
| Compost 30% | 1.0 cu yd | $42.00 |
| Perlite 10% | 5 bags | $90.00 |
YardWise — quantity estimates only. Prices are the ones you entered. yw/print
Free to use. No sign-up, no paywall, no hidden charge.
How this calculator works
A raised bed is a box, so its soil is area × depth — but people buy it as a blend, and a blend has to survive rounding. This tool sizes the soil for any number of beds, then splits it into topsoil, compost and perlite and rounds each component on its own.
The split is a design position, not a recommendation: the presets are example starting points and every share is editable. Shares are normalised and must total 100 % or the tool refuses the input with a message rather than quietly reshaping your mix.
Each bulk component rounds up to the yard's increment and perlite rounds up to whole bags. A guard prints when rounding pushes any component more than 15 % over its computed volume — a 10 % share rounded up can distort a blend much more than a 60 % share can.
The per-component cost table is the point: it shows what each part of the blend costs at your prices, and the total against the volume actually needed.
The formula, in symbols
F1 A_bed = bed length × bed width
A = A_bed × number of beds
F4 V = A × depth
F5 V′ = V × (1 + waste ÷ 100)
F10 V′_k = V′ × share_k ÷ 100
F6 bulk component : q = ⌈(V′_k ÷ 27) ÷ step⌉ × step
F7 bagged component: n = ⌈V′_k ÷ bag volume⌉
cost = Σ q_k × price_k
Worked example — the values this page starts with
F1 A_bed = 4.0 × 8.0 = 32.0 sq ft ; A = 32.0 × 3 = 96.0 sq ft
F4 d = 10 ÷ 12 = 0.8333 ft ; V = 96.0 × 0.8333 = 80.0 cu ft
F5 V′ = 80.0 × 1.10 = 88.0 cu ft = 3.259 cu yd
F10 topsoil 60 % = 52.8 cu ft = 1.956 cu yd → ⌈1.956 ÷ 0.5⌉ × 0.5 = 2.0 cu yd → $68.00
compost 30 % = 26.4 cu ft = 0.978 cu yd → 1.0 cu yd → $42.00
perlite 10 % = 8.8 cu ft ÷ 2 cu ft = 4.4 → 5 bags → $90.00
total = $200.00
bought: 3.0 cu yd + 10 cu ft of bags = 3.37 cu yd against 3.26 needed
Prices are example values, and the 60/30/10 split is an example starting point. Change either; the arithmetic does not care.
Questions people ask
How much soil for a 4 × 8 raised bed?
A 4 × 8 ft bed is 32 sq ft. At 10 inches deep that is about 26.7 cu ft, and with the 10 % default overage about 29.3 cu ft — set your actual depth and the tool does it.
How do I split soil between topsoil, compost and aeration?
This tool does not recommend a recipe. The 60/30/10 preset is an example you can edit, and the shares must total 100 % before the tool will compute.
Why did rounding put my blend off?
A small share rounds up to a whole increment, so 8.8 cu ft of perlite becomes five 2 cu ft bags (10 cu ft). The tool prints a warning when rounding adds more than 15 % to any component, because that is where a blend starts to move.
How deep should a raised bed be?
Not a question this tool answers. Depth is an input, and no recommended depth appears anywhere on the site: bed depth depends on what you are growing and on the structure, which a quantity estimate cannot judge.
Can I use garden soil instead of a mix?
The material choice is yours. The component prices and shares are editable, so you can cost whatever you intend to buy; the tool only does the arithmetic.
Formula: F1, F4, F5, F10 with F6/F7 — bed area, volume, overage, then a per-component split and rounding.
Density: topsoil 2300 lb/cu yd (secondary - primary unverified), compost 1000 lb/cu yd (secondary - primary unverified), both read 2026-11-05. Perlite is bought by the bag; no density is used.
Bag size: perlite 2 cu ft option, REG-05 (secondary - manufacturer body text for 0.75 cu ft and 50 lb; retailer/catalogue for 2 cu ft; aggregate volume derived from SAKRETE yield statement; Home Depot/Lowe's/Ace/Rona/McCoy's/Blain's/Tractor Supply blocked the fetcher).
Overage: 10 % is our default — change it in the form.
Prices: you enter them; the shown price is an example.
Last updated: 2026-11-05 — see Methodology & Sources.
Found a number that looks wrong? Tell us on the contact page — we cite the source for every constant and correct errors in public with the date.