Common footing sizes
| Footing | Concrete per 10 ft |
|---|---|
| 12 × 6 in | 0.19 yd³ |
| 16 × 8 in | 0.33 yd³ |
| 20 × 10 in | 0.51 yd³ |
| 24 × 12 in | 0.74 yd³ |
Concrete Footing Calculator
Work out concrete for strip/continuous footings under walls and foundations. Enter the total run length plus the footing width and depth.
Results update as you type.
Shape
ft
in
in
Identical pours (e.g. 6 piers)
%
5–10% typical
Bags & pricing
$
$/yd³
Concrete needed
0.72yd³
- Cubic feet
- 19.6
- 0.554 m³
- Bags (80 lb bag)
- 33
- 2,640 lb
- Ready-mix order
- 0.75 yd³
- Rounded to ¼ yd³
- Bagged cost
- —
- Add a bag price
Mix it yourself
Small pour — bagged or site-mixed concrete is cheaper and avoids ready-mix minimums and short-load fees.
How we calculate
volume (ft³) = total length (ft) × width (in) ÷ 12 × depth (in) ÷ 12
volume (yd³) = ft³ ÷ 27 · order = volume × (1 + waste %)
volume (yd³) = ft³ ÷ 27 · order = volume × (1 + waste %)
Trenched footings poured without forms are rarely perfectly square — use 10–15% waste for earth-formed trenches.
Frequently asked questions
How do I calculate concrete for a footing?
Multiply the total footing length (ft) by the width and depth (in inches, divided by 12 each). A 40 ft run of 16 × 8 in footing is 40 × 1.333 × 0.667 = 35.6 ft³ = 1.32 yd³.
How big should a footing be?
Typical residential continuous footings are 16–24 in wide and 8–12 in deep, below the local frost line. Size depends on soil bearing capacity and loads — your local code (IRC Table R403.1) or engineer sets the minimum.
How do I measure total footing length?
Add up the centre-line length of every footing run. For a rectangular foundation that’s the perimeter; add interior bearing-wall footings separately.
How much concrete for deck footings?
Deck piers are usually round: use the round column option. A 12 in diameter pier 4 ft deep is 3.14 ft³ — about 6 × 80 lb bags each.
Should footings have rebar?
Yes — typically two continuous #4 bars near the bottom, supported on chairs with 3 in of concrete cover. Check local code.
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