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Footing Concrete Calculator

Length, width and depth to yards and bags.

Also known as footing volume · pad footing concrete · strip footing concrete

Quick answer

With the default inputs: Length 40 ft · Footing width 16 in · Footing depth 8 in etc.Concrete required 1.45 yd³

Use your own dimensions ↓

Inputs

ft
in
in
strips
%

Result

Concrete required
1.45yd³
Net volume35.6ft³
With waste39.1ft³
Yards per linear foot0.0329yd³/ft
80 lb bags66bags
Total weight5671lb
Short tons2.84ton
How this is worked out

A strip footing is a box: length x width x depth, with width and depth divided by 12 when given in inches. The yards per linear foot line is the useful one - measure the total run and multiply instead of re-entering parameters. Footings overlap at L and T intersections so the true volume is slightly less than shown, but the waste allowance more than covers it. This figure excludes the gravel blinding layer, which is calculated separately - typically 4-6 in thick and 6 in wider than the footing each side.

Next up: Concrete Volume Calculator · Concrete Mix Design Calculator

Formula

Volume = L × (W/12) × (D/12) × runswidth and depth inches to feet
Cubic yards = volume ÷ 27
Yards per ft = (W/12 × D/12) ÷ 27multiply by total length
One 40 ft run at 16 in wide and 8 in deep with 10% waste: 40 × 1.333 × 0.667 = 35.6 ft³, 39.1 ft³ with waste = 1.45 cubic yards, about 66 bags of 80 lb. That is 0.033 cubic yards per linear foot.

How to work it out

  1. Measure total footing length off the drawings, taking corners on the centreline without double counting.
  2. Fix width and depth - 16 x 8 in is typical, 20 x 10-12 in for two storeys.
  3. Volume = total length x width/12 x depth/12 x number of runs.
  4. Add 10% waste and convert to cubic yards.
  5. The gravel blinding is separate: 4-6 in thick and 6 in wider each side, not part of the concrete.

Where it goes wrong

Material and cost

Concrete for strip footings at 3500 psi including pumping runs about USD 150-220 per cubic yard, with a short-load fee on small pours. Excavation, formwork, steel and placing as a package commonly comes in at 25-60 per linear foot depending on depth and soil. Rock excavation or a deep trench needing shoring doubles that. Formwork and labour usually cost more than the concrete.

On site

Basis

FAQ

How wide and deep should the footing be?
A single-storey house strip footing commonly runs 16 in wide by 8 in deep with two #4 continuous bars; two storeys or heavier loads go to 20 in wide and 10-12 in deep. The actual size comes from the drawings and local code, and poor bearing soil needs more width or depth. The governing check is that the base area keeps soil pressure below bearing capacity - a stronger mix will not fix an undersized footing.
Why is a gravel blinding layer needed?
The gravel layer spreads the load, gives a flat dry surface to work on, and breaks capillary rise. Pouring straight onto soil lets cement paste bleed into the ground, so the effective thickness drops and strength with it, and cover to the reinforcement cannot be controlled. Four to six inches is enough and it does not need heavy compaction.
Do I need to correct for corner overlaps?
No. Adding the run lengths double counts the intersection, but the corner is the same concrete in practice, so that volume is not real. Overlap typically runs 3-8% of the total against a 10% waste allowance, so the two broadly cancel and the answer stands. On very short runs with many corners the overlap share rises - drop the waste to 5% in that case.

Cite this page

Use this format in reports, method statements or coursework. The link is permanent.

Building Calculator. Footing Concrete Calculator. 2026-10-25. https://jianzhujisuan.com/en/footing-concrete

Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.