TryBuildCalcM20 Column Concrete Calculator (Rectangular & Circular — Volume, Cement, Sand & Aggregate)
Calculate column concrete volume and materials.
Estimate M20-style column concrete materials with cement, sand, aggregate, and wastage. Adjust column type, height, width/depth or diameter, count, mix ratio, and wastage for your RCC estimate.
🕒 Last updated: August 5, 2026
Inputs
ℹ️Rectangular/Square uses Height x Width x Depth. Circular uses the circle area (pi x (Diameter/2)^2) x Height — a genuinely different formula, not just a relabeled rectangle.
Cost
Showing results for 8 columns
Concrete Volume
2.484 m³ / 87.7 cft
(0.310 m³ / 11.0 cft per column)
Total Wet Volume: 2.484 m³ / 87.7 cft
Dry Volume: 3.825 m³ / 135.1 cft
Sand: 1.043 m³ / 36.8 cft
Aggregate: 2.087 m³ / 73.7 cft
(Per column: Sand 0.130 m³ / 4.6 cft, Aggregate 0.261 m³ / 9.2 cft)
Cement Required
(Including 5% Wastage)
22 bags
(3 bags per column)
Extra (Wastage): 1.00 bags
Setting up column formwork for this pour? Column Formwork Process Guide →
Approximate results for planning only. Verify with a professional.
Looking for the verification checklist, reference tables, tips, or common mistakes?See the complete Concrete Column Calculator.
M20 column material estimate
This page uses a 1:1.5:3 nominal mix for column concrete material planning.
The calculator is pre-filled for this column use case. Edit any input and the worked example updates from the active values.
- Mix: 1:1.5:3.
- Column size: 230 x 450 mm.
- Count: 8 columns.
How does the concrete column calculator work?
Wet volume depends on the column shape — Rectangular/Square uses the cross-section area (Width × Depth), while Circular uses the circle area instead. Every shape then follows the same dry-volume, mix-ratio, and wastage steps.
Step 1 — Rectangular / Square
Step 2 — Circular
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 |
|---|---|
| Column Type | Rectangular / Square Column |
| Height | 3 m (3 m) |
| Width | 230 mm (0.23 m) |
| Depth | 450 mm (0.45 m) |
| Count | 8 |
| Concrete Mix | M20 (1:1.5:3) |
| Wastage | 5% |
Step 1 — Wet Volume
| Calculation | Substitution | Result |
|---|---|---|
| H × W × D × Count | 3 × 0.23 × 0.45 × 8 | 2.484 m³ / 87.7 cft |
Step 2 — Dry Volume
| Calculation | Substitution | Result |
|---|---|---|
| Dry Volume = Wet Volume × 1.54 | 2.484 × 1.54 | 3.825 m³ / 135.1 cft |
Step 3 — Materials & Cement Bags
| Material | Share of Mix (1:1.5:3) | Result |
|---|---|---|
| Sand | 1.5 / 5.5 | 1.043 m³ / 36.8 cft |
| Aggregate | 3 / 5.5 | 2.087 m³ / 73.7 cft |
| Cement Bags (with 5% wastage) | 1 / 5.5 | 22 bags |
Therefore, this rectangular / square column needs approximately 2.484 m³ / 87.7 cft of concrete, requiring 22 cement bags, 1.043 m³ / 36.8 cft sand, and 2.087 m³ / 73.7 cft aggregate (including 5% wastage on cement).
Cross-check against the Column Type & Mix Reference table in the complete Concrete Column Calculator.