Free estimator
Raised Bed Soil Calculator
Find how much soil to buy for your raised garden beds. Calculate cubic feet, cubic yards, litres and whole bags from the space you plan to fill.
Last updated: October 8, 2026
How to measure a raised bed
Measure the inside length and width, then the depth of new soil you need. A 24-inch-tall bed does not require 24 inches of new soil if it already contains soil or filler. For several identical beds, enter the bed count; for different sizes, calculate each volume separately.
Soil volume and bag formula
cubic feet = length(ft) × width(ft) × depth(in) / 12 × beds
cubic yards = cubic feet / 27
litres = cubic feet × 28.316846592
bags to buy = round up(total volume / bag volume)
The estimate includes the measured fill space only. Soil can settle, but there is no universal extra percentage for every mix. Confirm any top-up allowance with your supplier. Round bags only after adding the volume for all your beds.
Soil for common raised bed sizes
These examples use inside dimensions, one bed and a 12-inch soil fill depth. Six inches of soil needs half these volumes; 18 inches needs one and a half times as much.
| Bed size | Cubic feet | Cubic yards | 2 cu ft bags |
|---|---|---|---|
| 4 × 4 ft | 16 | 0.59 | 8 |
| 4 × 8 ft | 32 | 1.19 | 16 |
| 4 × 12 ft | 48 | 1.78 | 24 |
Before ordering soil
Compare bagged soil by its labelled volume and bulk soil by cubic yard or cubic meter. This tool estimates quantity, not the best soil recipe. Confirm that your mix is suitable for raised beds and the plants you intend to grow.
For further reading, see University of Minnesota Extension's raised bed gardening guide.
FAQ
How much soil do I need for a 4x8 raised bed?
Using inside dimensions of 4 by 8 feet, a 12-inch soil fill depth needs 32 cubic feet, about 1.19 cubic yards or 906 litres. That is 16 bags of 2 cubic feet. At 6 inches deep, the same bed needs half as much.
How many bags of soil do I need for a raised bed?
Divide the total fill volume by the volume printed on each bag, then round up to whole bags. For example, 32 cubic feet divided by 1.5 cubic feet per bag is 21.33, so buy 22 bags. Use the same volume units for both numbers.
Can I calculate soil from 40 lb bags?
Not reliably from weight alone. Soil weight varies with moisture and composition. Use the bag's stated cubic feet or litres, or ask the supplier for its volume.
Should I use the full height of the raised bed?
Use the actual depth you intend to fill with new soil. Leave any intended headspace and exclude existing soil or bottom filler. Measure the inside length and width rather than outside dimensions.
Does the calculator choose a soil mix or planting depth?
No. It calculates purchase volume from your measurements. Choose a mix and rooting depth suitable for your crops and growing conditions, with advice from your supplier or local extension service.
Can I estimate several beds at once?
Yes, enter the number of identical beds. If beds have different dimensions, calculate each separately and add their volumes before rounding the final bag count.