Solve backwards
How big a raised bed will my soil fill?
- 32 ft³The example worked below
- Garden Soil CalculatorEvery figure is its own
You have
How much raised bed soil?
That is 32 ft³(906.1 L). Worked by the Garden Soil Calculator at the settings below.
The settings it uses
- Fill depth
- 12 in
- Settlement allowance (%)
- 20
What it will do
26.7 sq ft of raised bed
2.48 m²
One raised bed. Enough for a raised bed 8.2 × 3.3 ft at 12 in deep.
Or several. Less than one raised bed of the size the Garden Soil Calculator opens on (a raised bed 10 × 4 ft at 12 in deep).
Check it forwards
- Bed length
- 8.16 ft
- Bed width
- 3.27 ft
- It asks for
- 32 ft³
- You have
- 32 ft³
The Garden Soil Calculator asks for 32 ft³ at that size.
If you had more, or less
Around your amount
Each worked by the Garden Soil Calculator at the same settings.
Half
16 ft³
13.3 sq ft
a raised bed 5.8 × 2.3 ft at 12 in deep
Yours
32 ft³
26.7 sq ft
a raised bed 8.2 × 3.3 ft at 12 in deep
Half as much again
48 ft³
40 sq ft
a raised bed 10 × 4 ft at 12 in deep
Double
64 ft³
53.3 sq ft
a raised bed 11.5 × 4.6 ft at 12 in deep
Common amounts
What each amount of raised bed soil covers
The sizes it is usually sold in, each worked by the Garden Soil Calculator at the settings above.
| You have | It covers | As one raised bed | Average raised beds |
|---|---|---|---|
| 8 ft³(226.5 L) | 6.67 sq ft(0.62 m²) | a raised bed 4.1 × 1.6 ft at 12 in deep | under 1 |
| 16 ft³(453.1 L) | 13.3 sq ft(1.24 m²) | a raised bed 5.8 × 2.3 ft at 12 in deep | under 1 |
| 32 ft³(906.1 L) | 26.7 sq ft(2.48 m²) | a raised bed 8.2 × 3.3 ft at 12 in deep | under 1 |
| 64 ft³(1,812.3 L) | 53.3 sq ft(4.95 m²) | a raised bed 11.5 × 4.6 ft at 12 in deep | 1 |
The soil drops after the first watering
Loose topsoil and compost blends settle 15 to 25 per cent after watering and initial consolidation, and the calculator orders twenty per cent extra for it. Read backwards, the same twenty per cent comes off what you have: a bed filled level on the day finishes low, so the bed here is the one your soil fills once it has settled.
Measure inside the frame
Length and width are the space being filled, inside face to inside face. A 2 m bed made of 100 mm sleepers holds 1.8 m of soil, and measuring across the boards buys about a tenth too much on a small bed. Beds taper slightly, so measure at soil level rather than at the top of the boards.
Depth follows what you grow
About 200 mm, 8 inches, suits salads and herbs; 300 mm, 12 inches, most vegetables — the calculator's opening depth; 450 mm, 18 inches, or more for root crops and perennials. A deeper bed dries out more slowly, which matters more to most plants than the extra room for roots — but the same soil fills only two-thirds the area at 450 mm that it fills at 300.
How the answer is worked
Nothing here is a second formula. The Garden Soil Calculator runs forwards — a size in, a quantity out — and this page grows its own starting raised bed in proportion until the quantity it asks for is what you have. Where it rounds up to whole containers, the answer is the largest size before the next one would be needed.
Where the calculator adds an allowance for cuts or breakage when you order, the same allowance comes off here, because it is the same calculator: a stack you already own finishes less than its face value. Where it adds none, neither does this page — the settings beside the answer say which.
Garden Soil Calculator
runs it forwardsWork out the soil or growing medium a bed needs, with the settlement allowance that stops it looking half-full a month later.
Work out what to buy insteadSolve backwards
Other things you might already have
How big a bed will my bags of mulch cover?
Bagged mulch, worked by the Mulch Calculator.
How much bed will a yard of mulch cover?
Bulk mulch, worked by the Mulch & Gravel Calculator.
How much ground will my gravel cover?
Gravel, worked by the Mulch & Gravel Calculator.
How big a bed will my topsoil fill?
Topsoil, worked by the Topsoil Calculator.
How much ground will my compost dress?
Compost, worked by the Compost Blend Calculator.
How big a slab will a yard of concrete pour?
Ready-mix concrete, worked by the Concrete Calculator.
Solve backwards
Start from what is already in the yard
Paint, sheets, rolls, bags and pieces, each read the other way by the calculator that orders it.
The calculator's own figures
Nothing is estimated twice: the page runs the same calculator you would order with.
The largest size that fits
Where a calculator rounds up to whole containers, the answer stops before the next one.
Both unit systems
Gallons and litres, square feet and square metres, side by side.
Frequently asked questions
- How much raised bed does 32 ft³ of raised bed soil cover?
- At the Garden Soil Calculator's own settings, 26.7 sq ft (2.48 m²) — a raised bed 8.2 × 3.3 ft at 12 in deep. Every figure follows the settings, which you can change in the calculator.
- How much raised bed does 1,000 L of raised bed soil cover?
- At the Garden Soil Calculator's own settings, 2.78 m² (29.9 sq ft) — a raised bed 2.6 × 1.1 m at 300 mm deep. Every figure follows the settings, which you can change in the calculator.
- How many bags of soil does a 4 by 8 raised bed need?
- A 4 by 8 foot bed 12 inches deep holds 32 cubic feet (0.9 m³) finished. Order about a fifth more for settling — roughly 38 to 40 cubic feet, or 19 to 20 bags of 2 cubic feet. In metric that is about 1.1 m³, or 19 bags of 60 litres.
- How deep should a raised bed be?
- About 8 inches (200 mm) for salads and herbs, 12 inches (300 mm) for most vegetables, and 18 inches (450 mm) or more for root crops and perennials. Deeper beds hold moisture longer, which often matters more than the extra rooting depth.
- Why did the soil in my raised bed sink?
- Because loose soil and compost settle 15 to 25 per cent after watering and consolidation, and compost-rich blends settle more than mineral topsoil. Fill to the rim with about a fifth extra, or plan to top up after the first few weeks.