How to calculate soil
Cubic feet = length (ft) × width (ft) × depth (in) ÷ 12 Cubic yards = cubic feet ÷ 27 Cubic metres = length (m) × width (m) × depth (cm) ÷ 100 Order volume = bed volume × (1 + extra%) Bags = round up(order volume ÷ bag volume)
Worked example. Soil to order: 0.81 cubic yards.
Example inputs — Measurements: Feet / inches; Length: 10 ft; Width: 4 ft; Depth: 6 in; Extra allowance: 10%; Bag volume: 2 cu ft; Price per cubic yard: $40.00. Starting values are illustrative.
From George Guju, founder of Calculyn · Educational calculator guidance, not professional advice.
How it works
Measure the inside length and width of the bed and the depth you actually want to fill. Convert inches to feet or centimetres to metres before multiplying. Add an allowance for uneven ground, settling and handling, then choose bulk volume or round up to whole bags using the bag's labelled volume. For several beds, calculate each one and add the volumes; for irregular spaces, split the area into rectangles. A soil mix is not automatically suitable for every plant: confirm drainage, composition and the desired root depth separately.
Assumptions & limitations
- Rectangular bed with uniform fill depth; subtract existing fill before entering depth.
- Extra allowance is user-selected, not a guaranteed settling rate.
- Bag counts are rounded up; bulk cost excludes delivery, tax and supplier minimums.
- Volume only: no weight estimate because soil density and moisture vary.
Formula and assumptions reviewed October 2026 by the Calculyn team. How we build our calculators
Frequently asked questions
How many bags of soil do I need for a raised bed?
Divide the required volume including your extra allowance by the volume printed on each bag, then round up to a whole bag. Use matching units; a bag's weight alone does not establish its volume.
How do I convert cubic feet of soil to cubic yards?
Divide cubic feet by 27, because one cubic yard is a cube three feet long on each side: 3 × 3 × 3 = 27 cubic feet.
Should I add extra soil for settling?
You may add a planning allowance, but settling depends on the soil blend and how it is placed. The calculator starts with an illustrative 10% allowance; adjust it using your supplier's advice.
Can this calculate the weight of topsoil?
No. Weight depends on moisture and density. Ask the supplier for the density of the actual product rather than assuming a fixed weight per cubic yard.