Garden Bed Calculator
Work out how much soil raised garden beds need — from the bed size and the number of beds, in cubic yards and bags.
A raised bed is a box, and the soil is the box's volume — length times width times height, times the number of beds. This calculator is that one job, with bags and cost.
For a bed on flat ground rather than a raised box, use the soil calculator.
Your results
Enter your measurements and press Calculate.
Quantities are rounded up to whole tiles, planks, boxes or bags, after the wastage allowance. Cost appears only when you enter a price.
Formula
All lengths are converted to a single unit before the calculation: 1 ft = 0.3048 m, 1 in = 25.4 mm, 1 ft² = 0.09290304 m², 1 yd² = 9 ft². Material quantities are rounded up — you cannot buy part of a tile, plank or bag.
How to use this calculator
- Measure one bed — length, width and height.
- Enter how many identical beds you are filling.
- Enter the bag volume from the packaging.
- Add a price per bag if you want a cost estimate.
Worked example
| Beds | 2 beds, each 8 ft × 4 ft × 1 ft high |
|---|---|
| Soil per bed | 8 × 4 × 1 = 32 ft³ |
| Total | 2 × 32 = 64 ft³ = 2.37 yd³ |
| With 10% wastage | 64 × 1.10 = 70.4 ft³ = 2.61 yd³ (1.99 m³) |
| Bags (40 L bags) | ⌈1.99 ÷ 0.04⌉ = 50 bags |
Check it by hand: every step above uses the formula in the box. If your numbers match the example inputs but the calculator gives a different answer, please report it via the contact page.
Frequently asked questions
How much soil do I need for a raised bed?
Multiply length × width × height. An 8 × 4 ft bed, 1 ft high, needs 32 ft³ — and two of them need 50 bags of 40 L with wastage. This calculator does it for any bed size and count.
How deep should a raised bed be?
1–2 ft (300–600 mm) is normal. Shallow beds (6 in) suit herbs and salads; deep beds (18–24 in) suit root vegetables. The bed height is the soil depth here.
Should I fill the whole bed with soil?
For deep beds, fill the bottom half with logs, branches or coarse compost (hugelkultur) and the top 12 in with good soil — it saves money and the wood breaks down slowly. This calculator assumes full soil; adjust the height if you layer.
What soil should I use in a raised bed?
A mix of topsoil and compost (roughly 60/40) works for most vegetables. Pure topsoil compacts; pure compost shrinks. Use the soil and compost calculators for the two parts.
Related calculators
Estimates only. Results are for planning. Measure twice, confirm box coverage and tile sizes on the packaging you buy, and follow the manufacturer's instructions. See the disclaimer.