Concrete Calculator
Estimate volume, bags, and cost for your concrete project.
📐 Your Concrete Estimate
— m³
Mix breakdown (per bag): —
Volume based on standard concrete density: 2400 kg/m³. Actual may vary by mix design and aggregates.
Formula used: —
What is a Concrete Calculator?
This concrete calculator estimates the volume of concrete required for slabs, footings, columns, walls, steps, tubes, cones, and spheres. It also calculates the number of cement bags needed based on your chosen mix ratio, and provides a total cost estimate. Perfect for DIY projects, contractors, and quick material planning.
How to Use This Concrete Calculator
- Select shape – choose from 8 project shapes: Slab, Footing, Column, Wall, Steps, Tube, Cone, or Sphere.
- Enter dimensions – each shape has specific required measurements (length, width, height, diameter, radius, etc.).
- Choose mix ratio – standard, foundation, high strength, or lean concrete.
- Set bag weight – the weight of one cement bag (kg).
- Enter cost per bag – to get the total cost.
- Click "Calculate Concrete" – view volume, bags, and cost instantly.
How the Calculation Works
The calculator uses standard geometric formulas for each shape:
- Slab / Wall: Volume = Length × Width × Thickness
- Footing: Volume = Length × Width × Depth
- Column / Cylinder: Volume = π × (Radius)² × Height
- Steps: Volume = (Rise × Run × Width) × Number of Steps
- Tube / Pipe: Volume = π × (Outer Radius² − Inner Radius²) × Length
- Cone / Pile: Volume = (1/3) × π × (Radius)² × Height
- Sphere / Dome: Volume = (4/3) × π × (Radius)³
Total volume (m³) is converted to cubic yards and feet. Bags are calculated by dividing total concrete mass (volume × density 2400 kg/m³) by bag weight. The mix ratio determines the proportion of cement in the total mix.
Frequently Asked Questions (FAQ)
What is the standard concrete mix ratio?
The most common mix ratio is 1:1.5:3 (cement:sand:aggregate) for general use. For foundations, 1:2:4 is often used. High strength applications use 1:1:2.
How many bags of concrete do I need for a 10x10 slab?
For a 10×10×0.15m slab (4 inches thick), volume ≈ 1.5 m³. Using 40kg bags, you would need about 90 bags (approximate).
Can I use this calculator for circular columns?
Yes, select "Column / Cylinder" and enter the diameter and height. The calculator uses π × r² × height.
Does the calculator account for waste?
No, it estimates net volume. We recommend adding 5–10% extra for waste, spills, and variations.
What density does the calculator use?
We use 2400 kg/m³ (standard concrete density). This can vary based on mix design and aggregates.
How do I convert cubic meters to cubic yards?
Multiply m³ by 1.30795 to get cubic yards. The calculator does this for you automatically.
What is the difference between a slab and a footing?
A slab is a flat horizontal surface (like a floor), while a footing is a structural element that transfers loads to the soil. Both use the same volume formula but typically have different dimensions.
How do I calculate concrete for steps?
Each step is a rectangular prism. The calculator multiplies rise × run × width × number of steps to get total volume.
