Soil & compost
Choose an application depth for your material and project.
- Volume = total area × depth. Extra loose fill is an editable allowance for uneven ground and settlement, not a universal compaction factor.
Garden calculator
Soil & Compost Calculator
Plan soil, compost, topsoil and raised-bed layers with bag or bulk quantities.
What does a worked calculation look like?
Covering 5 × 4 m at 10 cm deep needs 2 m³ of soil. With a 10% allowance for settling that is 2.2 m³ (2,200 L, about 77.7 ft³), which is exactly 55 bags of 40 L.
Method and practical checks
- Volume = total area × depth. Extra loose fill is an editable allowance for uneven ground and settlement, not a universal compaction factor.
Amazon
Recommended supplies
As an Amazon Associate I earn from qualifying purchases.How the Soil & Compost Calculator works
Every calculation option
Raised-bed layers
Add each material layer separately; existing fill and solid objects reduce the depth you need to fill.
- Each layer deducts its own occupied volume before adding loose-fill allowance. Bags round up separately for each material; surplus compost cannot replace a shortfall of soil.
Topsoil & bulk
Use the supplier’s bulk density and choose bag or bulk delivery quantities.
- Mass = loose volume × entered density. The example density is only a working assumption; moisture and material composition change it.
Worked example
Covering 5 × 4 m at 10 cm deep needs 2 m³ of soil. With a 10% allowance for settling that is 2.2 m³ (2,200 L, about 77.7 ft³), which is exactly 55 bags of 40 L.
| Input | Value |
|---|---|
| Material | Soil |
| Measured sections | Length 5 m, Width 4 m |
| Fill depth | 10 cm |
| Additional loose fill | 10 % |
| Pack size | 40 L |
| Result | Value |
|---|---|
| Net volume | 2 m³ |
| Loose volume | 2.2 m³ |
| Loose volume in cubic feet | 77.692 ft³ |
| Required quantity | 2,200 L |
| Packs to buy | 55 |
| Purchase quantity | 2,200 L |
| Left over | 0 L |
Reading the result
- Bagged soil and compost are sold by loose volume in litres. Bulk deliveries are often sold by weight, so use the supplier’s density for them.
- New raised beds settle; the allowance keeps the surface near the top after the first months.
- Different materials (soil, compost, grit) are rounded separately because surplus compost cannot make up a shortfall of soil.
Sources and further reading
- RHS: mulches and mulching — Organic mulch at least 5 cm and ideally 7.5 cm thick, kept off woody stems.
How do litres relate to cubic metres of soil?
One cubic metre is 1,000 litres. A bed measuring 2 × 1 × 0.3 m requires 0.6 m³, or 600 L, before allowance or existing material. The tool calculates volume; bag weight varies with the material and moisture and is not a reliable substitute for labelled litres.
Should I fill the entire measured depth with new soil?
Subtract usable existing material where the chosen mode allows it. Consider the desired finished level and whether the product settles, but enter any settling allowance explicitly. The calculator does not prescribe a suitable soil mixture for a particular plant or drainage problem.
How do I convert the volume into bags?
Divide the required litres by the litres stated on each bag and round up to whole bags. A calculated 600 L fill therefore needs fifteen 40 L bags before any separately entered allowance. Check whether existing soil occupies part of the measured space; the full geometric volume need not all be new material.
Calculation/content reviewed 4 October 2026. Source: Babushka Market’s displayed formulas, units and labelled editable assumptions. How the estimates work