Concrete Footing Calculator (Isolated, Strip & Circular — Volume, Cement, Sand & Aggregate)

Calculate footing concrete volume and materials.

Estimate concrete volume and material quantities — cement, sand, and aggregate — for Isolated/Pad, Strip/Continuous, or Circular/Pier footings.

🕒 Last updated: August 4, 2026

Inputs

Footing Type

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ℹ️Isolated/Pad supports a single column. Strip/Continuous runs under a wall or a closely spaced row of columns — same formula as Isolated, just usually a much longer run. Circular/Pier is a round base, common under a single steel column or post.

Footing Length

ℹ️The plan length of a single footing.

Footing Width

Footing Thickness

RCC Footing Thickness →|Concrete Cover Guide →

Number of Footings

Concrete Mix

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What do concrete grades mean? M5 to M40 explained →

Wastage

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Cost

Enable Cost Estimation?

Concrete Volume: 0.675 m³ / 23.8 cft

Total Wet Volume: 0.675 m³ / 23.8 cft

Dry Volume: 1.039 m³ / 36.7 cft

Sand: 0.283 m³ / 10.0 cft

Aggregate: 0.567 m³ / 20.0 cft

Cement Required (Including 5% Wastage): 6 bags

Extra (Wastage): 0.27 bags

Approximate results for planning only. Verify with a professional.

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What is a Concrete Footing Calculator?

A concrete footing calculator estimates the volume of concrete and the quantity of materials — cement, sand, and aggregate — required for RCC footings. Footings are the base of a structure that transfer loads from columns or walls to the soil, so getting the concrete order right the first time matters: footings are difficult and expensive to reorder mid-pour.

This calculator covers all three common footing shapes: Isolated/Pad (a single rectangular slab under one column), Strip/Continuous (a long rectangular run under a wall or row of closely spaced columns), and Circular/Pier (a round base, common under a single steel column or post).

Using this calculator helps you:

Estimate concrete volume for any of the three common footing shapes
Calculate cement, sand, and aggregate quantities
Plan materials for multiple footings or a long strip run
Reduce wastage and cost overruns
Improve construction planning accuracy

This calculator estimates concrete materials only — see the Footing Steel Calculator for reinforcement, and Limitations below for what this doesn't cover.

How does the concrete footing calculator work?

Wet volume depends on the footing shape — Isolated and Strip share the same rectangular formula, while Circular uses the circle area instead. Every shape then follows the same dry-volume, mix-ratio, and wastage steps.

Step 1 — Isolated / Strip (Rectangular)

Wet Volume = Length × Width × Thickness × Count

A Strip footing uses the exact same formula — its "Length" is just a wall run instead of a small pad.

Step 2 — Circular / Pier

Wet Volume = π × (Diameter / 2)² × Thickness × Count

Enter the diameter, not the radius — the formula already halves it.

Step 3 — Convert to Dry Volume

Dry Volume = Wet Volume × 1.54

The 1.54 factor accounts for voids in aggregates, sand bulking, and material loss during mixing.

Step 4 — Split by Mix Ratio

Cement = (Cement Ratio ÷ Total Ratio) × Dry Volume — same for Sand and Aggregate

Step 5 — Convert Cement Volume to Bags

Cement Bags = Cement Volume ÷ 0.0347

Step 6 — Add Wastage

Final Cement Bags = Calculated Bags × (1 + Wastage %)

Step 7 — Cost (Optional)

Total Cost = (Cement Bags × Price/Bag) + (Sand Volume × Price/Volume) + (Aggregate Volume × Price/Volume)

All three quantities are priced at their wastage-adjusted amount — the quantity you'd actually order, not the theoretical minimum before wastage. Sand and aggregate prices can be entered per m³ or per cft — whichever unit you enter is converted to match the volume automatically.

Worked Example

This example uses the active inputs above and follows the same steps as the Formula section.

Input Values Used

Input	Value
Footing Type	Isolated / Pad Footing
Length	1.5 m (1.5 m)
Width	1.5 m (1.5 m)
Thickness	300 mm (0.3 m)
Count	1
Concrete Mix	M20 (1:1.5:3)
Wastage	5%

Step 1 — Wet Volume

Calculation	Substitution	Result
L × W × T × Count	1.5 × 1.5 × 0.3 × 1	0.675 m³ / 23.8 cft

Step 2 — Dry Volume

Calculation	Substitution	Result
Dry Volume = Wet Volume × 1.54	0.675 × 1.54	1.039 m³ / 36.7 cft

Step 3 — Materials & Cement Bags

Material	Share of Mix (1:1.5:3)	Result
Sand	1.5 / 5.5	0.283 m³ / 10.0 cft
Aggregate	3 / 5.5	0.567 m³ / 20.0 cft
Cement Bags (with 5% wastage)	1 / 5.5	6 bags

Therefore, this isolated / pad footing needs approximately 0.675 m³ / 23.8 cft of concrete, requiring 6 cement bags, 0.283 m³ / 10.0 cft sand, and 0.567 m³ / 20.0 cft aggregate (including 5% wastage on cement).

Cross-check against the Footing Type & Mix Reference table below.

Footing Type & Mix Reference

Footing Type	Typical Use	Volume Formula
Isolated / Pad	Single, well-spaced column	L × W × T
Strip / Continuous	Load-bearing wall or closely spaced column row	L × W × T (long run)
Circular / Pier	Single steel column or post	π × (D/2)² × T

Concrete Mix Ratios for Footings

Footings transfer structural loads to soil, so higher-grade concrete improves stability and durability in aggressive ground conditions.

M20 (1:1.5:3) — common for residential footings, mild-to-moderate exposure
M25 (1:1:2) — used for heavier loads or aggressive soil (waterlogged, chemically active, coastal)
M30+ — used for high-rise structures or very severe exposure

How to Use This Concrete Footing Calculator

Select Footing Type — Isolated/Pad, Strip/Continuous, or Circular/Pier, matching the structural drawing.
Enter Length and Width (Isolated/Strip) or Diameter (Circular).
Enter the footing thickness/depth.
Enter the number of identical footings (or strip runs).
Select the concrete mix grade and wastage allowance.
Review the concrete volume, cement bags, sand, and aggregate, and cross-check against the Verification Checklist before ordering.

Concrete Footing Tips & Best Practices

Always confirm the footing type against the structural drawing before ordering — an Isolated pad and a Strip run of similar cross-section produce very different total volumes.
For circular footings, double-check that you've entered the diameter, not the radius — this is the single most common manual-calculation error, and it changes volume by 4x.
Include a pedestal/column stub volume separately if it's cast monolithically with the footing — it's frequently missed in manual takeoffs.
Use 3-5% wastage for formed footings poured with ready-mix concrete; use 7-10% for site-mixed concrete or irregular footing shapes.
Order slightly more than the calculated volume for footings — reordering mid-pour means stopping dewatering and risking a cold joint.
Compare your result against the Concrete Footing Verification Checklist before finalizing an order.

Common Mistakes to Avoid

Entering radius instead of diameter for a Circular footing. The formula uses (Diameter/2) internally — entering the radius there halves it again, understating volume by 4x.
Treating a Strip footing's length as a small pad dimension. A strip run is usually 10-30 m, not 1-2.5 m — entering a pad-sized length under-orders concrete for the actual wall run.
Incorrect unit conversion between mm, cm, m, in, and ft on any dimension.
Ignoring the footing count — forgetting to update it after adding or removing footings from the layout.
Not applying the dry volume factor, understating cement/sand/aggregate quantities by roughly 35%.
Incorrect mix ratio selection for the soil exposure condition specified on the drawing.
Ignoring wastage, leaving no margin for spillage or site losses on a pour that's difficult to reorder mid-session.

Limitations of this calculator

Does not include reinforcement steel — use the Footing Steel Calculator separately
Assumes uniform footing dimensions — does not model stepped or trapezoidal (combined) footing shapes
Does not account for soil bearing capacity or check whether the footing size is structurally adequate
Does not include pedestal/column stub volume automatically — add it separately if cast monolithically
Actual material usage may vary on site due to formwork tolerance and spillage
The optional cost estimate covers cement, sand, and aggregate only, at prices you enter — it excludes excavation, formwork, reinforcement, labor, and transport, and doesn't reflect live market rates

For structural adequacy (bearing capacity, footing size, reinforcement design), always refer to a qualified structural engineer's drawings and soil investigation report.

Related Calculators

Use the PCC Calculator to estimate the blinding layer cast below this footing before reinforcement is fixed.

Use the Footing Steel Calculator to size the reinforcement mesh once the footing volume is confirmed.

The Concrete Column Calculator estimates concrete for the column loads this footing transfers to the soil.

Use the Beam Load Calculator to estimate the loads feeding into column and footing sizing.

If isolated footings would overlap or the soil bearing capacity is too low, use the Raft / Mat Foundation Calculator for one continuous foundation slab instead.

If the soil is too weak or too deep for a shallow footing to work at all, use the Pile Foundation Calculator to size deep pile shafts instead.

FAQ

Isolated/Pad is a single rectangular slab under one column — the most common residential footing. Strip/Continuous runs under a wall or a closely spaced row of columns, so its "length" is a wall run (often 10-30 m) rather than a small pad's 1-2.5 m. Circular/Pier is a round base, common under a single steel column or post. Isolated and Strip actually share the same Length x Width x Depth formula since a strip footing is mathematically just a very long rectangular footing — only Circular uses a different formula (pi x (Diameter/2)^2 x Depth).

Isolated and Strip: Volume = Length x Width x Depth x Number of footings, all in meters. Circular: Volume = pi x (Diameter/2)^2 x Depth x Number of footings. All dimensions should be converted to meters before calculating to get cubic meters directly.

This almost always means diameter and radius got swapped somewhere in a manual cross-check. The formula uses (Diameter/2), so if you (or a spreadsheet you're comparing against) accidentally used the full diameter as if it were the radius, the resulting area — and therefore volume — comes out 4x too high. Footings are dimensioned by diameter on drawings; enter the diameter here, not the radius.

A dry volume factor of 1.54 is applied to the wet (as-cast) volume for all three footing shapes, to account for voids between aggregates, bulking of sand, and material losses during mixing and transportation. Without it, cement/sand/aggregate quantities would be underestimated by roughly 35%.

For M20 concrete (1:1.5:3), roughly 8 bags of cement are required per cubic meter of wet volume before wastage. The exact count scales with the mix ratio (richer mixes like M25 need more cement per m³) and the wastage percentage you select.

M20 (1:1.5:3) is standard for residential footings in mild-to-moderate exposure. M25 (1:1:2) is used where soil is aggressive (waterlogged, chemically active, or coastal) or loads are heavier. M30+ is reserved for high-rise or very severe exposure conditions — confirm the exact grade from the structural drawing, since it's driven by soil exposure class, not just building size.

Strip/Continuous footings are used under load-bearing walls or when a row of columns is spaced closely enough that separate isolated footings would overlap or nearly touch — combining them into one continuous run is both simpler to form and often more economical than several adjacent pads. Isolated footings are used for well-spaced individual columns.

Wastage (typically 3-5% for formed footings with ready-mix concrete, up to 7-10% for site-mixed concrete) accounts for spillage, over-excavation fill, and minor site losses during placement, ensuring enough material is ordered to complete the pour in one continuous session — footings are difficult to reorder quickly mid-pour.

Yes — set the footing count to the number of identical footings (or pier bases) you're pouring, and the calculator scales the total concrete and material quantities accordingly. For a Strip footing, count is usually 1 (a single continuous run); use it if you have multiple separate strip runs of the same cross-section.

No — this estimates concrete materials only (volume, cement, sand, aggregate). Use the site's dedicated Footing Steel Calculator to size the reinforcement mesh, bar spacing, and steel weight separately.

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