Soil & Topsoil Calculator
Calculate topsoil, compost or mulch volume and weight for beds and lawns.
Please note: Material estimates for planning only. Always confirm quantities against your drawings, local building codes and supplier specifications before ordering. Structural work requires a qualified engineer.
What the Soil & Topsoil Calculator does
Soil and mulch are sold by volume in bags or bulk bags, so the calculation is area times depth. Weight matters for delivery and handling — a cubic metre of topsoil is well over a tonne.
Formula
Area = Length × Width, or π × (Diameter ÷ 2)² for a circleVolume = Area × DepthLitres = Volume × 1,000Weight = Volume × Density
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Area shape | one of 2 options | Yes | — |
| Length | number | In some modes | Accepts more than 0. Shown Area shape is Rectangular. |
| Length unit | one of 6 options | In some modes | Shown Area shape is Rectangular. |
| Width | number | In some modes | Accepts more than 0. Shown Area shape is Rectangular. |
| Width unit | one of 6 options | In some modes | Shown Area shape is Rectangular. |
| Diameter | number | In some modes | Accepts more than 0. Shown Area shape is Circular. |
| Diameter unit | one of 6 options | In some modes | Shown Area shape is Circular. |
| Depth | number | Yes | Accepts more than 0. |
| Depth unit | one of 5 options | Yes | — |
| Material density | kg/m³ | Yes | Topsoil 1300, compost 700, bark mulch 350. Accepts 100 or more. |
| Bag size | litres | Yes | Accepts 1 or more. |
| Price per m³ | selected currency | Optional | Accepts 0 or more. |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose Area shape and Depth unit.
- Enter Depth, Material density and Bag size.
- Fill in the remaining inputs the form shows for your choice.
- Optionally add Price per m³.
- Select Calculate.
Worked example
A 10 m × 5 m bed at 150 mm depth with topsoil at 1,300 kg/m³, 50-litre bags.
- Length
- 10 m
- Width
- 5 m
- Depth
- 150 mm
- Density
- 1300
Area 50 m², volume 7.5 m³ = 7,500 litres = 150 bags, weighing 9.75 tonnes.
Frequently asked questions
How deep should topsoil be for a lawn?
100–150 mm of good topsoil supports turf. Planting beds want 300–450 mm for root development.