Footing Calculator – Size by Soil Bearing

A reliable footing takeoff follows one rule: measure twice, order once. The calculator converts your column load and soil bearing class into dependable quantities using Footing Area = Column Load ÷ Allowable Bearing Pressure, then adds the waste margin that experienced builders apply by default. Example: An 80 kN column on 150 kPa soil needs 0.53 m² - a 0.8 × 0.7 m pad or 0.75 m strip. Field tip: Check bearing, then doubling: footing width ≈ 2 × wall thickness. The result is broken down into purchasable units - bags, sheets, rolls or truck loads - so you can order the nearest whole unit without overbuying, and every figure traces back to the formula shown above.

1. 1

   Measure the space

   Record the column load and soil bearing class at the widest and longest points.

2. 2

   Enter the values

   Type the measurements into the calculator and select your units.

3. 3

   Apply the formula

   The tool computes Footing Area = Column Load ÷ Allowable Bearing Pressure for your inputs instantly.

4. 4

   Add waste and order

   Review the total with a 5-10% margin and round up to whole units.

• Skipping reinforcement

• Backfilling too early

• Footings above frost line