Strip Footing Concrete Calculator: Concrete Volume for a Continuous Run

A strip footing concrete quantity is the pour volume of one continuous footing run: measured length multiplied by measured width and measured thickness. Enter those three dimensions and the calculator returns the geometric volume, then adds a waste percentage only when you have a project reason for it.

How much concrete does a strip footing need?

You need the measured pour volume plus a documented waste allowance. The calculator shows the measured result first in cubic yards and cubic feet, or cubic metres and litres, and keeps it visible while a user-entered waste percentage builds a separate planning volume. The strip footing measurement guide shows where to take each dimension in the field.

Which measurements do you need?

You need the total run length, the poured concrete width, and the concrete thickness for one uniform strip footing run. Enter each in the units printed beside the field.

Run length

Measure one continuous run, or add straight sections that share the same width and thickness. Measure corners on the centreline so each corner is counted once.

Footing width

Measure the poured concrete base width, not the trench top. Formed trenches and over-digged sections differ, and the concrete quantity follows the placed width.

Concrete thickness

Measure from the bearing surface to the top of the pour. The concrete thickness is not the depth below grade; soil cover above the footing adds nothing to the pour volume.

What formulas does the calculator use?

The calculator converts width and thickness to the base length unit (metres or feet), multiplies the 3 values, and converts the result to the displayed volume units. It retains full JavaScript precision during the calculation and displays up to 3 decimal places.

Measured volume = run length × footing width × concrete thickness

Planning volume = measured volume × (1 + waste % ÷ 100)

NIST Handbook 44 Appendix C supplies the cited volume relationships. Unit switching converts populated dimensions and clears the displayed result, so a fresh calculation runs in the selected units.

Worked imperial example

A strip footing run is 120 ft long, 16 in wide, and 8 in thick, with a documented 10% waste allowance.

1. Width in feet: 16 ÷ 12 = 1.333... ft. Thickness in feet: 8 ÷ 12 = 0.666... ft.
2. Volume in cubic feet: 120 × 1.333... × 0.666... = 106.667 ft³.
3. Volume in cubic yards: 106.667 ÷ 27 = 3.951 yd³.
4. Planning volume at 10% waste: 3.951 × 1.10 = 4.346 yd³, or 117.333 ft³.

Measured result: 3.951 yd³ and 106.667 ft³. Planning result: 4.346 yd³ with the entered 10% waste. The waste stays visible as a separate assumption.

Worked metric example

A strip footing run is 25 m long, 40 cm wide, and 20 cm thick, with no waste entered.

1. Width and thickness in metres: 0.40 m and 0.20 m.
2. Volume: 25 × 0.40 × 0.20 = 2.0 m³.
3. Equivalent volume: 2.0 × 1,000 = 2,000 L.

Measured result: 2.0 m³ and 2,000 L. With 0% waste the planning volume is identical, so the record shows one checkable number.

Common strip footing concrete mistakes

• Using the trench top width instead of the placed concrete width.
• Measuring thickness below grade instead of from the bearing surface to the top of the pour.
• Double counting corners by measuring each run to the outer edge.
• Entering inches in a feet field or centimetres in a metres field.
• Using one average width or thickness across sections that change.
• Applying waste before preserving the measured volume.
• Treating the planning volume as a check that the footing is sized correctly.
• Using a borrowed waste percentage as if it were measured.

What does this calculator not do?

This calculator computes concrete quantity. It does not size the footing width or depth, select concrete strength, design reinforcement, set frost depth, or confirm code compliance. Those are structural design decisions for the project drawings and the responsible professional. Quantity planning never replaces them.

How do you handle corners and stepped footings?

Measure runs on the centreline so each corner belongs to exactly one run. A corner measured into both adjoining runs inflates the total by one footing width times thickness times the corner overlap.

When the width or thickness changes, split the footing into separate runs, calculate each run at its own dimensions, and add the unrounded measured volumes. Stepped footings are a series of rectangular runs at different depths; run the calculator once per step. The strip footing length guide shows the centreline method, and the Concrete Footing Calculator handles stepped and overlapping sections when those need explicit overlap control.

How should waste be recorded?

Waste starts at 0% so the first result stays a checkable measurement. Add a percentage only when the project record supports it, and keep the measured volume visible beside the planning volume.

No universal waste percentage is published here because spillage, over-dig, placement method, and supplier practice vary by project. A 5% or 10% figure borrowed from another project is not evidence.