TryBuildCalcM20 Footing Concrete Calculator (Isolated, Strip & Circular — Volume, Cement, Sand & Aggregate)
Calculate footing concrete volume and materials.
Estimate M20-style footing concrete materials with cement, sand, aggregate, and wastage. Adjust footing type, dimensions, count, mix ratio, and wastage for your foundation estimate.
🕒 Last updated: August 4, 2026
Inputs
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.
ℹ️The plan length of a single footing.
Cost
Showing results for 8 footings
Concrete Volume
8.100 m³ / 286.0 cft
(1.012 m³ / 35.8 cft per footing)
Total Wet Volume: 8.100 m³ / 286.0 cft
Dry Volume: 12.474 m³ / 440.5 cft
Sand: 3.402 m³ / 120.1 cft
Aggregate: 6.804 m³ / 240.3 cft
(Per footing: Sand 0.425 m³ / 15.0 cft, Aggregate 0.851 m³ / 30.0 cft)
Cement Required
(Including 5% Wastage)
69 bags
(9 bags per footing)
Extra (Wastage): 3.27 bags
Approximate results for planning only. Verify with a professional.
Looking for the verification checklist, reference tables, tips, or common mistakes?See the complete Concrete Footing Calculator.
M20 footing material estimate
This page uses a 1:1.5:3 nominal mix for footing concrete material planning.
The calculator is pre-filled for this footing use case. Edit any input and the worked example updates from the active values.
- Mix: 1:1.5:3.
- Count: 8 footings.
- Includes cement bags.
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)
A Strip footing uses the exact same formula — its "Length" is just a wall run instead of a small pad.
Step 2 — Circular / Pier
Enter the diameter, not the radius — the formula already halves it.
Step 3 — Convert to Dry Volume
The 1.54 factor accounts for voids in aggregates, sand bulking, and material loss during mixing.
Step 4 — Split by Mix Ratio
Step 5 — Convert Cement Volume to Bags
Step 6 — Add Wastage
Step 7 — Cost (Optional)
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 | 450 mm (0.45 m) |
| Count | 8 |
| Concrete Mix | M20 (1:1.5:3) |
| Wastage | 5% |
Step 1 — Wet Volume
| Calculation | Substitution | Result |
|---|---|---|
| L × W × T × Count | 1.5 × 1.5 × 0.45 × 8 | 8.1 m³ / 286.0 cft |
Step 2 — Dry Volume
| Calculation | Substitution | Result |
|---|---|---|
| Dry Volume = Wet Volume × 1.54 | 8.1 × 1.54 | 12.474 m³ / 440.5 cft |
Step 3 — Materials & Cement Bags
| Material | Share of Mix (1:1.5:3) | Result |
|---|---|---|
| Sand | 1.5 / 5.5 | 3.402 m³ / 120.1 cft |
| Aggregate | 3 / 5.5 | 6.804 m³ / 240.3 cft |
| Cement Bags (with 5% wastage) | 1 / 5.5 | 69 bags |
Therefore, this isolated / pad footing needs approximately 8.1 m³ / 286.0 cft of concrete, requiring 69 cement bags, 3.402 m³ / 120.1 cft sand, and 6.804 m³ / 240.3 cft aggregate (including 5% wastage on cement).
Cross-check against the Footing Type & Mix Reference table in the complete Concrete Footing Calculator.