TryBuildCalcCircular Footing Calculator (Isolated, Strip & Circular — Volume, Cement, Sand & Aggregate)
Calculate footing concrete volume and materials.
Calculate concrete volume and materials for circular (pier) footings under a single column or post. 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.
ℹ️Enter the diameter, not the radius — using the radius here would understate volume by a factor of 4.
Cost
Showing results for 4 footings
Concrete Volume
0.942 m³ / 33.3 cft
(0.235 m³ / 8.3 cft per footing)
Total Wet Volume: 0.942 m³ / 33.3 cft
Dry Volume: 1.451 m³ / 51.2 cft
Sand: 0.396 m³ / 14.0 cft
Aggregate: 0.792 m³ / 28.0 cft
(Per footing: Sand 0.099 m³ / 3.5 cft, Aggregate 0.198 m³ / 7.0 cft)
Cement Required
(Including 5% Wastage)
8 bags
(2 bags per footing)
Extra (Wastage): 0.38 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.
4 circular piers, 1 m diameter x 300 mm thick
A circular (pier) footing uses Volume = pi x (Diameter/2)^2 x Thickness — a genuinely different formula from a rectangular footing, since it's based on the circle's area rather than length x width. For 4 piers at 1 m diameter and 300 mm thick, total wet volume is 0.942 m³, dry volume 1.451 m³, needing about 8 cement bags (1:1.5:3 mix, 5% wastage), 0.396 m³ sand, and 0.792 m³ aggregate.
The calculator is pre-filled for this footing use case. Edit any input and the worked example updates from the active values.
- Default: 4 piers, 1 m diameter, 300 mm thick.
- Formula: pi x (D/2)^2 x T x Count.
- ~8 cement bags with 5% wastage (1:1.5:3 mix).
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 | Circular / Pier Footing |
| Diameter | 1 m (1 m) |
| Thickness | 300 mm (0.3 m) |
| Count | 4 |
| Concrete Mix | M20 (1:1.5:3) |
| Wastage | 5% |
Step 1 — Wet Volume
| Calculation | Substitution | Result |
|---|---|---|
| π × (D / 2)² × T × Count | π × (1 / 2)² × 0.3 × 4 | 0.942 m³ / 33.3 cft |
Step 2 — Dry Volume
| Calculation | Substitution | Result |
|---|---|---|
| Dry Volume = Wet Volume × 1.54 | 0.942 × 1.54 | 1.451 m³ / 51.2 cft |
Step 3 — Materials & Cement Bags
| Material | Share of Mix (1:1.5:3) | Result |
|---|---|---|
| Sand | 1.5 / 5.5 | 0.396 m³ / 14.0 cft |
| Aggregate | 3 / 5.5 | 0.792 m³ / 28.0 cft |
| Cement Bags (with 5% wastage) | 1 / 5.5 | 8 bags |
Therefore, this circular / pier footing needs approximately 0.942 m³ / 33.3 cft of concrete, requiring 8 cement bags, 0.396 m³ / 14.0 cft sand, and 0.792 m³ / 28.0 cft aggregate (including 5% wastage on cement).
Cross-check against the Footing Type & Mix Reference table in the complete Concrete Footing Calculator.