How do I calculate footing concrete?

For a flat isolated pad, multiply length by width by depth, then by the number of footings. Stepped or sloped footings must be split into parts and summed.

Does this include the PCC levelling course?

No. The plain cement concrete bed below the footing is a separate item with its own thickness and mix; run the concrete volume calculator for it.

Can I use this for a raft foundation?

Only very roughly, by treating the raft as one large pad. Real rafts have thickened bands, drops under columns and edge upturns that this simple prism ignores.

Does this include the lean concrete bed?

No. The PCC or lean concrete levelling course sits below the footing and is a separate pour with its own dimensions. Add it as its own calculation. The same applies to pedestals, plinth beams and any working-space over-excavation you intend to backfill with concrete.

Footing concrete calculator — isolated footing volume and steel

Concrete volume for isolated pad footings from plan size and depth, across the number of footings, with an indicative reinforcement weight.

footing

Dimensions inyou enter

Number of footingsyou enter

Footing lengthyou enter

Footing widthyou enter

Footing depthyou enter

Ordering

Wastage allowanceyou enter

Wastage is site-specific. Order allowance, breakage and cutting loss differ by material, supplier and workmanship; enter your own figure.

Steel intensityyou enter

kg / cu m

Your assumption, used only for an indicative weight. Replace it with a bar bending schedule before ordering.

Result — calculated from your inputs

Concrete to order25.200 cu m

In cubic feet889.93 cu ft

Indicative steel(at the intensity you entered)1,467.95 kg

Working

Net volume864.00 cu ft

Net volume in cubic metres24.466 cu m

Order volume25.200 cu m

Steel weight1,467.95 kg

Continue to a full site assessment

A calculator answers one question. A DevPartner assessment carries planning capacity, programme, cost, revenue, deal structure and cash flow through one deterministic model and freezes a versioned decision report.

Nothing from this calculator maps into the assessment intake, so you will start from a blank site. No opportunity is created until you save one.

Continue to a full site assessment See a sample decision report

How this calculator works

volume = count × dimension A × dimension B × dimension C
order  = volume × (1 + wastage %)
steel  = net volume (cu m) × steel intensity (kg/cu m)

You enter: A value you supply. Nothing is assumed for you.
Calculated: Arithmetic on your inputs, shown in the working.
Assumption: A factor or allowance you can change — mix ratios, wastage, dry-volume factors.
Approximation: Geometry or method that approximates reality; labelled wherever used.
Verify locally: Planning parameters, statutory rates and structural design must come from the authority or a qualified professional.

Pad footings only

This calculates a rectangular prism: a flat isolated pad footing of uniform depth. Sloped or stepped footings contain less concrete than the prism and need to be computed section by section. Raft slabs, combined footings, strip footings and pile caps all have different geometry and are outside this calculation.

Add the plain cement concrete levelling course separately if your specification includes one — it sits below the footing and is usually a different, leaner mix.

Over-excavation is a real cost in foundations

In loose or waterlogged ground, excavated sides slump and the actual concrete placed exceeds the designed volume, sometimes substantially. Foundation wastage allowances are commonly set higher than superstructure allowances for exactly this reason.

Where the ground is poor enough for this to matter, the foundation solution itself is usually the bigger cost question, and belongs in the full feasibility rather than a quantity calculator.

Worked example

Eight isolated footings at 1.5 m × 1.5 m × 0.6 m total 10.8 cubic metres of concrete. Add 5% for over-excavation and uneven bearing and the order becomes about 11.34 cubic metres.

Levelling course, lean concrete and pedestal volumes are separate rows — they are not inside the footing dimensions.

Mistakes in footing quantities

Omitting the lean concrete or PCC bed, which is poured before the footing and is a real, separately ordered quantity.

Using design dimensions where the excavated dimension is larger because of working space and side slope.

Treating footing steel intensity as transferable from slab or beam intensity.

This is quantity only, not foundation design

Footing size depends on bearing capacity, soil investigation, water table, loading and settlement criteria. Those come from a geotechnical report and a qualified structural engineer.

This page multiplies dimensions you already hold. It performs no foundation design of any kind.

Frequently asked questions

How do I calculate footing concrete?: For a flat isolated pad, multiply length by width by depth, then by the number of footings. Stepped or sloped footings must be split into parts and summed.
Does this include the PCC levelling course?: No. The plain cement concrete bed below the footing is a separate item with its own thickness and mix; run the concrete volume calculator for it.
Can I use this for a raft foundation?: Only very roughly, by treating the raft as one large pad. Real rafts have thickened bands, drops under columns and edge upturns that this simple prism ignores.
Does this include the lean concrete bed?: No. The PCC or lean concrete levelling course sits below the footing and is a separate pour with its own dimensions. Add it as its own calculation. The same applies to pedestals, plinth beams and any working-space over-excavation you intend to backfill with concrete.