Foundation Concrete & Rebar Calculator
The foundation concrete calculator determines the cubic volume of ready-mix concrete and linear meters of rebar steel required for strip footings, structural slabs, and pier foundations.
Geometric concrete volume: 16 m³
Reinforcement scheme
4 longitudinal rods d12mm + stirrup ties d8mm every 35cm with 10% overlap
Concrete grade guidance (M300)
M300 (B22.5) — Most popular for 2-story private residential homes with concrete floors.
How to use
- Select foundation geometry: continuous strip footing, monolithic slab, or pier/pad footing.
- Enter dimensions: total footing perimeter length, beam width, and depth.
- For raft slabs, enter length, width, and uniform slab thickness.
- For piers, enter column diameter, height, and unit count.
- Configure reinforcement cage options (bar diameter and continuous longitudinal runs).
- Review total ready-mix concrete volume (m³) and steel rebar requirements.
What Does the Foundation Calculator Compute?
Concrete volume: cubic meters required for ordering batch plant transit mixers.
Pouring buffer: standard 5% to 10% contingency for form deflection and soil absorption.
Reinforcement schedule: total linear meters of primary ribbed rebar and stirrups.
Formwork area: contact area of form boards or plywood panels.
Frequently Asked Questions
How is strip footing concrete volume calculated?
Multiply total centerline perimeter by footing width and depth (V = L × W × D).
How much concrete is needed for a 10×10 m footprint?
A typical strip footing requires 15 to 16 m³; a 25 cm thick structural slab requires 25 m³ of concrete.
What ordering contingency is standard?
Add a 5% to 10% safety margin to accommodate trench irregularities and concrete compaction.
What rebar size is required?
Deformed ribbed rebar sized 12 mm to 16 mm is standard for primary residential footing cages.
Which concrete compressive class is recommended?
Ready-mix concrete class C20/25 (M250) or C25/30 (M300) is standard for residential foundations.
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