Spread (Pad) Footing Calculator — m, m³, cost
How to use this calculator
Pick a footing shape, enter plan dimensions with the m/cm/mm selector, set the footing depth and quantity, and add a pedestal stub if the column starts above grade. The m³ output is what you order on pour day — round up to the next 0.25 m³ to avoid a minimum-load surcharge.
Cost — choose ready-mix per m³, 50 kg bags, or 25 kg bags. Select currency.
Reinforcement — bottom mat rebar in both directions per EN 1992-1-1 (Eurocode 2), bar size and spacing.
Labor — rate per footing, per m³, or flat price.
Saved Calculations
| Time | Shape | Qty | Vol m³ | Weight | Cost |
|---|
How to Calculate Concrete for Spread Footings (Metric)
A spread (pad) footing spreads a concentrated column load over enough soil so the ground pressure stays below the design bearing resistance from your geotechnical report (EN 1997-1). Choose a shape, enter plan dimensions with the m/cm/mm selector, set thickness and quantity, and add a pedestal stub for columns starting above the footing. The quantity below already includes the waste allowance — order ready-mix to the next 0.25 m³.
How to use it
Size the pad from the service load divided by the allowable soil pressure (e.g. 180 kN on 200 kPa soil ≈ 0.9 m², so a 1.0 m square pad). Use the Reinforcement tab for the bottom mat, the Cost tab with the currency selector to compare ready-mix vs. bagged, and the concrete pier or grade beam tools when pads tie together. Continuous wall footings go in the strip footing calculator; slabs over the pads in the slab calculator.
Footing Volume Formulas
Square: V = side² × depth. Rectangular: V = length × width × depth. Circular: V = π × (d/2)² × depth. Pedestal volume is added on top, total × number of footings, then × (1 + waste%). Concrete density is 2 400 kg/m³; bag counts use 0.024 m³ per 50 kg bag and 0.012 m³ per 25 kg bag. For exact bag math see the concrete bag calculator.
Reinforcement per EN 1992-1-1
The bottom mat runs both ways with a nominal cover of 50–75 mm for concrete cast against prepared ground (EN 1992-1-1 §4.4.1, exposure-class dependent). Minimum reinforcement follows As,min = 0.26·(fctm/fyk)·b·d. Bars Ø8–Ø20 mm at 100–300 mm centres; laps are taken at ≈ 40·Ø and standard stock is 6 m or 12 m. Heavier mats and column dowels into a cap belong in the pile cap calculator.
FAQ
How deep should a spread footing be? 300 mm is typical for light residential pads and 450–600 mm for commercial columns. The base must sit below the local frost depth on undisturbed or compacted ground.
What size footing do I need? Plan area = column service load ÷ allowable soil bearing pressure. Bearing resistance comes from a geotechnical investigation; a structural engineer should size and detail footings per EN 1992-1-1 and EN 1997-1.
How much extra concrete should I order? 5% for clean machine-dug holes, 10% typical, up to 15% for hand-formed or over-excavated pads. The quantity shown already includes this allowance.
On pour day
Three things estimators forget when pricing isolated pad footings. Minimum-load surcharge — most ready-mix plants charge €60–120 if you order under ~2 m³, so four 1.0 × 1.0 m × 30 cm pads (≈1.3 m³) often come in cheaper with 25/50 kg bags than a truck. Pedestal dowel projection — vertical dowels must extend out of the footing far enough to lap into the column above (typically 300–600 mm plus a 40·ø splice per EN 1992-1-1 §8.7), so order rebar at footing depth + projection, not just the pad thickness. Frost depth — the bottom of the footing must sit below the local frost line (80–120 cm in Central Europe); a 30 cm pad poured shallow will heave. Typical 2025 EU prices: €110–160 per m³ delivered (min-load surcharge below ~2 m³), €6–9 per 50 kg bag, €2.30–3.20 per linear metre of Ø12 B500B rebar. Save runs to History and export the diagram as text, CSV, A4 JPG, or PDF — estimates are planning numbers, not a substitute for a structural drawing.
