Concrete Footing Calculator
Use this concrete footing calculator to estimate how much concrete you need for a footing before ordering materials. It is useful for strip footings, pad footings, and similar foundation pours where you need a quick volume check, bag estimate, or rough cost. Enter the footing dimensions and let the calculator work out the concrete quantity based on the shape and units supported by the tool.
V = L × W × D
Recommended: 10% for standard conditions
How this calculator works
This calculator works out the volume of concrete needed for a footing by multiplying the relevant footing dimensions together. For strip and pad footings it multiplies length × width × depth after converting all inputs to metres. For round footings, it uses the circular cross-section formula and multiplies by depth. All inputs support mixed units: each dimension has its own unit selector (m, mm, ft, or in) and the calculator converts to metres before calculating. Waste is then applied to give the volume with allowance, and the order recommendation is rounded up to the nearest 0.25 m³.
Formulas used
volume = length × width × depth
radius = diameter / 2
volume = π × radius² × depth
volume with waste = volume × (1 + waste % / 100)
bags = ⌈volume with waste ÷ yield per bag⌉
cost = bags × cost per bag
or
cost = volume with waste × cost per m³
All dimensions are converted to metres before calculation. Bag yields used: 20 kg ≈ 0.01 m³, 25 kg ≈ 0.0125 m³. The order recommendation rounds the volume-with-waste up to the nearest 0.25 m³. Final ordering should always reflect actual footing dimensions, over-excavation, waste, and the bag yield or ready-mix method used on site.
Worked example
Take a strip footing measuring 6 m long, 0.45 m wide, and 0.6 m deep. The base volume is 6 × 0.45 × 0.6 = 1.62 m³. With a 10% waste allowance, the adjusted volume becomes 1.62 × 1.10 = 1.782 m³. The order recommendation rounds that up to the nearest 0.25, giving 2.00 m³. If bags are enabled, the calculator divides the adjusted volume by the yield per bag and rounds up to a whole number of bags.
What this calculator helps with
This tool helps with early material planning for footings and foundations so you can estimate concrete quantity before ordering bags or ready-mix. It is useful for small projects, extensions, outbuildings, walls, and other jobs where footing volume needs checking quickly. It is a planning tool only and does not replace structural design, engineering, or foundation sizing advice.
Frequently asked questions
Related tools
- Concrete Volume Calculator — volume for slabs, footings, columns and walls
- Concrete Slab Bag Calculator — how many bags of concrete for a slab
- Monolithic Concrete Slab Calculator — concrete volume for slabs with thickened edges
- Gravel Under Concrete Slab Calculator — sub-base volume, tonnes and bulk bags
Disclaimer: This calculator is for planning and estimating only. Actual concrete quantities vary with footing geometry, waste, over-excavation, and site conditions. Always confirm final requirements before ordering or pouring.