Footing Calculator
Calculate concrete for strip footings, pad foundations and pier holes.
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 Footing Calculator does
Footing concrete is the trench or hole volume. Strip footings run continuously under walls; pads carry individual columns; piers are circular holes, common for decks and fences.
Formula
Strip volume = Length × Width × DepthPad volume = Pad length × Width × Depth × CountPier volume = π × (Diameter ÷ 2)² × Depth × Count
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Footing type | one of 3 options | Yes | — |
| Total length | number | In some modes | Accepts more than 0. Shown Footing type is Strip footing (continuous trench). |
| Total length unit | one of 6 options | In some modes | Shown Footing type is Strip footing (continuous trench). |
| Width | number | In some modes | Accepts more than 0. Shown Footing type is Strip footing (continuous trench), or Footing type is Pad footings (rectangular). |
| Width unit | one of 5 options | In some modes | Shown Footing type is Strip footing (continuous trench), or Footing type is Pad footings (rectangular). |
| Depth | number | Yes | Accepts more than 0. |
| Depth unit | one of 5 options | Yes | — |
| Pad length | number | In some modes | Accepts more than 0. Shown Footing type is Pad footings (rectangular). |
| Pad length unit | one of 6 options | In some modes | Shown Footing type is Pad footings (rectangular). |
| Pier diameter | number | In some modes | Accepts more than 0. Shown Footing type is Circular piers. |
| Pier diameter unit | one of 5 options | In some modes | Shown Footing type is Circular piers. |
| Number of pads or piers | number | In some modes | Accepts 1 or more. Shown Footing type is Pad footings (rectangular), or Footing type is Circular piers. |
| Waste allowance | % | Yes | — |
| Concrete price per m³ | selected currency | Optional | Accepts 0 or more. |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose Footing type and Depth unit.
- Enter Depth and Waste allowance.
- Fill in the remaining inputs the form shows for your choice.
- Optionally add Concrete price per m³.
- Select Calculate.
Worked example
A 30 m strip footing, 600 mm wide, 300 mm deep, 10% waste.
- Type
- Strip
- Length
- 30 m
- Width
- 600 mm
- Depth
- 300 mm
Net 5.4 m³, order 5.94 m³ weighing 14.26 tonnes, excavating 6.24 m³.
Frequently asked questions
How deep should footings go?
Below the frost line and any soft ground — typically 450–1,000 mm depending on climate and soil. Local codes set the minimum.