Concrete Footing Calculator: measuring notes and method
Avoid double-counting intersections
Trace each footing run on the drawing and mark where it meets another. Measure non-overlapping lengths, or deduct the shared block at each intersection. Keep different footing widths or depths as separate project items.
When a slab and footing meet
Check whether the footing depth is measured from the top or underside of the slab. If the slab calculation already includes the upper portion, add only the remaining depth here.
CHECK A PRACTICAL EXAMPLE
An intersection counted twice
Two 5 m runs, each 400 mm wide and 300 mm deep, overlap over a 400 × 400 mm square. These dimensions are an example only.
Unadjusted 10 m total
- Material to order
- 1.2 m³
- Measured volume
- 1.2 m³
9.6 m after overlap deduction
- Material to order
- 1.152 m³
- Measured volume
- 1.152 m³
The shared block is 0.4 × 0.4 × 0.3 = 0.048 m³. Subtract it once. Check the drawing before assuming each intersection has this geometry.
Fixed comparison in metric units. Values are illustrative unless linked to a recorded project; changing the calculator above does not change this example.
Formula
Volume = length × width × depth × quantity. Order volume = volume × (1 + waste ÷ 100).
Product reference: QUIKRETE product yields
Worked examples in metric and imperial units
Illustrative values match Reset example and stay fixed when you edit the calculator. Both columns describe the same calculation; converted inputs are rounded.
Metric worked example
- Total footing length
- 20 m
- Footing width
- 0.4 m
- Footing depth
- 300 mm
- Quantity
- 1
- Waste allowance
- 10 %
Material to order: 2.64 m³
Imperial worked example
- Total footing length
- 65.6168 ft
- Footing width
- 1.3123 ft
- Footing depth
- 11.811 in
- Quantity
- 1
- Waste allowance
- 10 %
Material to order: 3.453 yd³
Follow the calculation
Lengths in this working are in metres.
- Measured volume = 20 × 0.4 × 0.3 × 1 = 2.4 m³.
- Allowance multiplier = 1 + 10 ÷ 100 = 1.1.
- Volume with allowance = 2.4 × 1.1 m³.
Unit conversions
1 m³ = 1,000 L ≈ 1.30795 yd³. One cubic yard is 27 ft³.
Reviewed 19 October 2026. How calculations are checked · Report a correction