How to use it
- Enter load in kN.
- Enter soil bearing capacity in kPa.
- Set safety factor and footing depth.
- Read the area, side length, and concrete volume results.
What it does – The Footer Calculator takes your design load, soil bearing capacity, safety factor, and footing depth to instantly tell you the required footing area, the side length of a square footing, and the concrete volume you’ll need. Why it matters – Getting the right footing size prevents settlement, structural failure, and costly redesigns. Reading the results – The footing area (m²) is the total surface that must resist the load; the side length is the square dimension you’ll cut the formwork to; the concrete volume (m³) tells you how much mix to order, based on the depth you entered. No guesswork, just clear numbers you can feed straight into your construction plans. The calculator also factors in the safety factor you set, ensuring the design stays within the allowable soil pressure. Because all inputs are in SI units, you can copy the results directly into structural spreadsheets or BIM models without conversion.
Pro tips
- Add 10% extra concrete for waste.
- Round the side length up to the nearest 0.1 m for formwork.
- Order steel reinforcement based on the final footing dimensions.
- Double‑check the safety factor; a common mistake is using 1.0 instead of 1.5.
Real-life examples
- A residential builder sizing footings for a new garage.
- A civil engineer verifying foundation dimensions for a small commercial shed.
- A DIY homeowner planning a patio foundation on variable soil.
Case study
Mike, a small‑contractor, entered a 150 kN load, 200 kPa soil capacity, a safety factor of 1.5, and a 0.6 m depth. The calculator returned a 0.75 m² area, 0.87 m side length, and 0.52 m³ concrete. With those numbers he ordered exact material, avoided over‑design, and completed the foundation two days ahead of schedule.