Concrete Footing Calculator

Size a continuous strip footing in one pass: concrete volume with waste, plus the total length and weight of continuous rebar based on how many rows the footing carries.

Footing Details

Total Footing Length (perimeter)

Footing Width

Footing Depth

Continuous Rebar Rows

Rebar Size

Waste / Overage

Enter your footing dimensions to see concrete and rebar needed.

The formula

Cubic Yards = (Length ft × Width in ÷ 12 × Depth in ÷ 12) ÷ 27

Footing width and depth are entered in inches and converted to feet. A common residential strip footing is 16 inches wide by 8 inches deep with two rows of continuous #4 rebar, but always follow your local code and soil conditions.

Rebar in footings

Continuous horizontal bars run the length of the footing — the calculator multiplies footing length by the number of rows and reports total length and weight for your steel order. Lap splices where bars meet add a little length; round your order up to whole sticks.

Frequently Asked Questions

How much concrete does a footing take?

A 100 ft footing at 16 in wide and 8 in deep is about 3.3 cubic yards before waste. Enter your dimensions above for an exact figure with a waste allowance.

What size rebar goes in footings?

#4 (1/2 inch) is the most common for residential strip footings, typically two continuous rows. Larger structures may call for #5 or more rows per the engineer’s design.

How deep should footings be?

Footings must bear below the local frost line on undisturbed soil — depth varies by region and code. The depth entered here is the concrete thickness of the footing itself, not the excavation depth.