Concrete Footing Calculator
This concrete footing calculator sizes strip footings, pad footers and deck footings. Enter the footing run, width and depth to get volume in cubic yards and cubic meters, bags required and estimated cost.
Como usar esta calculadora
- Insira suas dimensões — pés para comprimentos, polegadas para a espessura.
- Ajuste as opções — porcentagem de desperdício, tamanho do saco e o preço local do concreto.
- Leia seus resultados — volume, sacos, peso e custo são atualizados ao vivo enquanto você digita.
A fórmula
Footing volume = Length × Width × Depth. For multiple pads, multiply by the count. Exemplo resolvido: A 20 ft strip footing, 16 in wide × 12 in deep: 20 × 1.33 × 1 = 26.7 ft³ ÷ 27 ≈ 0.99 yd³ — order 1.1 yd³ with waste.
A concrete calculator for footings works exactly like a slab calculator rotated into the ground: length × width × depth. The difference is context — footings sit below grade, so over-excavation is normal and waste allowances of 10% (rather than 5%) are smart.
For deck footings poured in round forms, the geometry is cylindrical — use the sonotube calculator or post hole calculator for those. This page covers rectangular strip and pad footers, the kind that support foundation walls, garages and additions.
Typical residential strip footings are 16–24 inches wide and 8–12 inches deep, sized so the footing projects beyond the wall on both sides. Always match local frost depth: footings must bear below the frost line.
Perguntas frequentes
Perguntas comuns sobre a concrete footing calculator.
How much concrete do I need for footings?
Multiply footing length × width × depth in feet, divide by 27 for cubic yards. A 40 ft run of 16 × 8 in footing is 40 × 1.33 × 0.67 = 35.6 ft³ ≈ 1.32 yd³.
How deep should concrete footings be?
At minimum 12 inches below undisturbed soil, and always below the local frost line — which ranges from 12 inches in warm climates to 48+ inches in the north.
What about deck footings?
Deck footings are usually round piers — 8–12 inch diameter sonotubes on a wider base. Use our sonotube calculator for exact cylinder volumes.
Should footings be wider than the wall?
Yes — typically twice the wall thickness, so an 8 inch wall gets a 16 inch footing, centered, with the footing depth at least equal to the projection.
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