Concrete Calculator for Volume, Bags, and Cost
The concrete calculator estimates how much concrete you need for any pour, then converts that volume into bag counts and a material cost. Enter your dimensions for a slab, footing, column, wall, or other shape and get the result in cubic meters, cubic yards, and cubic feet instantly.
It covers 8 common construction shapes — slab, footing, circular slab, column (round or square), wall, stairs, curb, and tube — so you can size a driveway, foundation, or column base without working the geometry by hand. It is built for DIY builders, contractors, and anyone buying ready-mix or bagged concrete who needs a quick, reliable estimate.
How to Use the Concrete Calculator
Select a shape
Pick one of the 8 shape tabs — Slab, Footing, Circular Slab, Column, Wall, Stairs, Curb, or Tube. An interactive diagram shows exactly which dimensions to measure.
Enter dimensions
Fill in the measurements. Each field has its own unit selector (m, cm, ft, in), so you can mix units freely — for example length in feet and thickness in centimeters.
Adjust the waste factor
Use the Waste Factor slider (0–25%) to add a buffer for spillage and uneven ground. A 10% waste factor is typical for most projects.
Read the results
See the volume in cubic meters, cubic yards, and cubic feet, plus the number of bags needed. Choose your bag size (20kg, 25kg, 40kg, 50kg, 60lb, or 80lb) to update the count.
Build a multi-pour project
Enter a Price per m³ for a cost estimate, click Add to Project after each calculation to track combined totals, then Export PDF to download a report for the job site.
Features
8 Shape Calculators
Estimate concrete for slab, footing, circular slab, column, wall, stairs, curb, and tube — each with an interactive dimension diagram.
Per-Field Unit Conversion
Every measurement field supports meters, centimeters, feet, and inches, so you can mix units within a single calculation with no manual conversion.
Round & Square Columns
Switch a column between round and square types and set a quantity to size several identical columns in one go.
Adjustable Waste Factor
A 0–25% slider adds a buffer for spillage, over-excavation, and formwork imperfections so you order enough concrete.
Multiple Bag Sizes
Pick from 20kg, 25kg, 40kg, 50kg, 60lb, and 80lb bags; counts use the standard 2,400 kg/m³ concrete density and round up.
Cost Estimation
Enter your local price per cubic meter to see an instant material cost for the current pour and the whole project.
Multi-Section Project Builder
Add each pour as a section and track combined volume in m³ and yd³, total bag count, and overall cost as a running total.
PDF Export
Download a report with shape, dimensions, waste factor, volume in all units, bag estimates, and cost — ready to print or share.
Tube Validation
For hollow tubes the calculator checks that the outer diameter is larger than the inner diameter and warns you instead of returning impossible volumes.
Multi-Unit Volume Output
Every result shows volume in cubic meters, cubic yards, and cubic feet at once, so it works for any region or supplier.
Frequently Asked Questions
How much concrete do I need?
Select the shape that matches your pour, enter its dimensions, and the calculator returns the volume in cubic meters, cubic yards, and cubic feet. Add a waste factor (10% is typical) so you order a little extra to cover spillage and uneven ground.
How is the concrete volume calculated?
Each shape uses a standard geometry formula. A slab is Length × Width × Thickness, a circular slab is π × (Diameter ÷ 2)² × Thickness, and a tube is π × (outer radius² − inner radius²) × Length. All dimensions are converted to meters internally before the volume is calculated.
How are bag counts calculated?
The calculator uses a concrete density of 2,400 kg/m³ for a standard mix. It multiplies your volume by this density to get the total weight, then divides by your selected bag size and rounds up, since you cannot buy a partial bag.
What waste factor should I use?
A 10% waste factor is standard for most projects. Use 15–20% for uneven terrain or complex formwork, or around 5% for precise indoor pours on flat surfaces. The buffer covers spillage, over-excavation, and material left in the mixer.
Can I mix different units in the same calculation?
Yes. Each measurement field has its own independent unit selector, so you can enter length in feet, width in meters, and thickness in centimeters. The calculator converts everything to meters internally before computing the volume.
What is the difference between Slab and Footing?
Both are rectangular volumes. A Slab uses Length × Width × Thickness for flat surfaces like driveways and patios, while a Footing uses Length × Width × Depth for foundation bases below ground. The math is identical; the labels match standard construction practice.
Why does the Tube shape show a warning?
The Tube calculates the concrete in a hollow cylinder, so the outer diameter must be larger than the inner diameter — otherwise there is no wall thickness. If you enter an inner diameter equal to or larger than the outer one, the calculator shows a warning and returns zero volume.
Is my data stored or shared?
No. All calculations happen entirely in your browser. Your dimensions, prices, and results are never sent to a server or stored anywhere, and the PDF report is generated locally on your device.
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