Filling a raised bed
An 8 × 4 ft bed with a 12 in fill depth holds 32 ft³. With 10% allowance, the target is 35.2 ft³. Bags labeled 1.5 ft³ require 24 bags.
Fill beds from their internal dimensions, subtracting the soil already present.
Project measurements
For a circle or ring, enter the outside diameter.
Use one currency throughout; tax, labor and delivery excluded.
Prices use your chosen currency consistently. Blank price skips cost. Example coverage, density, yield and prices are editable scenarios, not current product offers.
Material takeoff
Estimated purchase quantity
88 bags
1 bed(s) · fill above existing soil
Illustration is schematic, not an installation drawing.
| Area per bed | 120 ft² |
|---|---|
| New fill depth | 12 in |
| Number of identical beds | 1 |
| Volume before allowance | 4.44 yd³ |
| Volume | 4.89 yd³ |
| Cubic feet | 132 ft³ |
| Liters | 3,737.82 L |
| Bulk alternative (rounded) | 5 yd³ |
| Bagged material cost | Not entered |
Method: Net interior bed area × (target depth − existing soil depth) × bed count × (1 + settlement allowance/100). Divide by bag volume; round up.
Use internal dimensions and the depth still to fill. Allowance adds material for expected loss or settling; it is not a prediction of final compaction. Existing soil, roots and drainage layers are represented only by the depths/exclusions you enter. Soil suitability and nutrients are excluded.
Quantity and material-only cost estimate. Verify field measurements, product instructions and your purchase units. Labor, delivery, taxes, equipment and structural adequacy are excluded.
Calculations run in your browser. This tool does not request a location, retrieve live prices or send your measurements to a material supplier.
How to use the Soil Calculator
- 01
Measure internal bed length and width, or diameter. Select the footprint and subtract unfilled patches.
- 02
Enter target depth and the existing soil depth, then the number of identical beds. The calculator uses the depth difference.
- 03
Enter bag volume and a settlement allowance you expect. Set bulk increment and optional bag price, then download the takeoff.
Examples
Topping up existing soil
The same bed with 10 in of existing soil and a target of 12 in needs only 2 in of new soil. At 10% allowance, that is about 5.87 ft³, or four 1.5 ft³ bags.
Use the volume inside the bed
Outside timber dimensions overstate usable soil space. Measure the inside footprint and the depth to the intended surface. This uniform-depth model treats all beds as identical; different sizes should be measured separately.
Settling is an allowance
Iowa State Extension illustrates bed volume as length × width × depth and converts cubic feet to cubic yards. Soil products also note that raised beds can settle over time. The extra percentage here is an input for your situation, not a predicted settlement rate or a soil recipe.
What to know
- Material quantities and user-price scenarios only; no structural adequacy, code compliance or installation approval.
- Example product values are illustrative. Verify your measurements and current product label before ordering.
Common questions
Can I calculate a top-up?
Yes. Enter the desired final depth and the existing soil depth. The difference must be positive; if the bed is already full, no new fill calculation is needed.
Are drainage layers included?
Only through your entered existing depth and exclusions. The tool does not choose a drainage construction or model water movement.
Can this select a growing medium?
No. Soil suitability, plant nutrients, drainage and blend proportions need separate consideration. This calculator estimates volume and purchase quantities.