Topsoil Calculator (Australia)
A 2.4 m × 1.2 m area 300 mm deep needs about 0.864 m³ (864 L) of topsoil, or 35 bags of 25 L.
Updated · Australian units: metres, millimetres, cubic metres · Built and checked by AI, which can make mistakes
Work out how much topsoil you need
Result
This is an estimate. Real quantities depend on uneven ground, settling, compaction and the exact product, and bag sizes and weights vary by brand. Check the bag or ask your supplier before you buy.
Built and checked by AI. AI wrote this calculator and its explanations, researched the rates and ran the tests. AI can make mistakes, and the checks may not catch them all, so confirm anything important with an official source or a qualified professional. How we use AI.
Quick answer
A 2.4 m × 1.2 m area 300 mm deep needs about 0.864 m³ (864 L) of topsoil, or 35 bags of 25 L.
Working in feet and inches? Use our US topsoil calculator.
How to use the topsoil calculator
- Choose the shape of the area: a rectangle, a circle, or enter the area if you already know it.
- Enter the measurements in metres and the depth in millimetres.
- Pick the bag size you plan to buy, and change the weight if your supplier quotes a different figure.
- Optionally open “Compare costs” to see whether bags or bulk is cheaper.
- Press Calculate to see how much you need, with the steps.
How it’s calculated
Area = length × width (m²), or π × (diameter ÷ 2)² for a circle
Volume (m³) = area (m²) × depth (mm) ÷ 1,000
Litres = m³ × 1,000
Bags = litres ÷ litres per bag, rounded up
Worked example
Topsoil for a 2.4 m × 1.2 m area at 300 mm
- Area: 2.4 m × 1.2 m = 2.88 m².
- Volume: 2.88 m² × 300 mm ÷ 1,000 = 0.864 m³.
- In litres: 0.864 m³ × 1,000 = 864 L.
- Weight: 0.864 m³ × 1.28 tonnes per m³ = 1.11 tonnes.
- Bags: 864 L ÷ 25 L per bag = 34.56, rounded up to 35 bags.
Buying topsoil in bags or bulk
Bagged soil is easy to carry for small beds, but the number of bags climbs quickly. For bigger jobs, bulk soil delivered by the cubic metre is often cheaper. Enter both prices in the calculator to compare. Loam weighs about 1,280 kg per cubic metre when dry, according to Engineering ToolBox, and more when moist or compacted.
Soil settles after it’s watered, so many gardeners add a little extra, especially when filling a raised bed.
When you’d actually use a topsoil calculator
- Filling a raised garden bed. Enter the bed’s inside length, width and depth.
- Levelling a lawn area. Work out how much soil to order before you start.
- Comparing bags and bulk. See which is cheaper for your job.
What this calculator doesn’t include
- Irregular shapes. Split the area into rectangles and circles and add the results.
- Settling and compaction. Organic materials settle after watering, so you may need a little more.
- Delivery fees, minimum orders and local prices, which vary by supplier.
How we calculate
Area comes from your measurements. Volume is area × depth ÷ 1,000, in cubic metres. Weight uses 1.28 tonnes per cubic metre unless you enter your own figure, from Engineering ToolBox’s density for loam. We calculate at full precision and round only for display. Bag counts are rounded up to whole bags.
Sources:
Frequently asked questions
How many bags of soil are in a cubic metre?
A cubic metre is 1,000 litres, so it takes 40 bags of 25 L soil, or about 34 bags of 30 L.
How much soil do I need for a raised bed?
Multiply the bed’s inside length, width and depth. A 2.4 × 1.2 m bed 300 mm deep needs 0.864 m³, or 864 litres.
Is it cheaper to buy soil in bulk?
For larger jobs it often is, but delivery fees and minimum orders vary. Enter both prices in the calculator to compare.