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Construction

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Construction

Concrete Strip Footing Calculator.

Estimates the volume of concrete needed for a strip footing, along with the estimated weight and number of concrete bags required.

Results update live as you type.
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Your inputs

How it works

  1. 1

    Measure the length, width, and depth of the footing in feet.

  2. 2

    Multiply length × width × depth to get the raw volume in cubic feet.

  3. 3

    Add the waste factor as a percentage of the raw volume.

  4. 4

    The result is the total concrete volume needed, including waste.

length * width * depth * (1 + waste / 100)

Frequently asked questions

What is a strip footing?

A strip footing is a continuous concrete base that supports a load-bearing wall, spreading the weight over a wider area.

Why include a waste factor?

Waste accounts for spillage, uneven excavation, and slight over-excavation, ensuring you order enough concrete.

How do I convert cubic feet to cubic yards?

Divide the cubic feet by 27, since 1 cubic yard equals 27 cubic feet.

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Results

Formula checked

Concrete Volume

66cu ft

Estimated Weight9570lb
60-lb Bags Needed147bags
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Estimate for general guidance only — verify important decisions with an appropriate professional.

How it works

Estimates the volume of concrete needed for a strip footing, along with the estimated weight and number of concrete bags required.

  1. Measure the length, width, and depth of the footing in feet.
  2. Multiply length × width × depth to get the raw volume in cubic feet.
  3. Add the waste factor as a percentage of the raw volume.
  4. The result is the total concrete volume needed, including waste.

Formulas

The math behind this calculator, written out so you can verify the result.

Volume of a rectangular prism

V = L × W × D

The volume of concrete is the product of the footing's length, width, and depth.

Example:

Input: L = 30 ft, W = 2 ft, D = 1 ft

Calculation: 30 × 2 × 1 = 60 cu ft

Result: 60 cubic feet

Waste adjustment

V_total = V × (1 + waste/100)

Add a percentage to the raw volume to cover material loss during placement.

Example:

Input: V = 60 cu ft, waste = 10%

Calculation: 60 × 1.10 = 66 cu ft

Result: 66 cubic feet

Real-world use cases

Where this calculation shows up in everyday life.

Ordering ready-mix concrete

Get the exact volume to order from a supplier, avoiding shortages or excess.

Example: For a 30 ft × 2 ft × 1 ft footing, order about 66 cu ft (2.44 cu yd).

Estimating bagged concrete

Determine how many 60-lb or 80-lb bags to buy for small projects.

Example: A 66 cu ft footing needs about 147 bags of 60-lb mix.

Budgeting material costs

Calculate the volume to estimate concrete cost and plan the project budget.

Example: Multiply volume by local price per cubic yard.

Tips and common mistakes

Tips

  • Always measure in feet; convert inches to feet by dividing by 12.
  • Add 5-10% waste for typical footings, more for irregular shapes.
  • Check local building codes for minimum footing dimensions.
  • For large volumes, consider ordering ready-mix instead of bagged concrete.

Common Mistakes to Avoid

  • Forgetting to convert inches to feet before calculating.
  • Not including a waste factor, leading to a shortfall.
  • Using the wrong bag yield (e.g., 60-lb bag yields about 0.45 cu ft).

Assumptions and limitations

  • Use the stated inputs and units.
  • Results are estimates for planning and education.
  • Check measurements and source data before making an important decision.