Concrete Calculator
Calculate concrete volume for rectangular slabs, footings, and round columns with an optional waste allowance.
What this calculator does
Concrete volume is length × width × thickness for a rectangular slab or footing. Enter the dimensions, quantity, and waste allowance to see cubic feet, cubic yards, and cubic meters.
Concrete dimensions
Rectangular volume uses length × width × thickness. Quantity is applied before waste.
Length × width × thickness × quantity, then waste.
The arithmetic uses the exact values shown above. Verify field measurements, product pack sizes, layout constraints, and local requirements before ordering or building.
How to interpret the result
The calculator reports geometric volume before waste and an order-planning volume after waste. Supplier minimums, subgrade variation, form movement, and placement loss can change the quantity purchased.
How the result is calculated
Slab or footing: length × width × depth. Column: π × radius² × height. Final volume = shape volume × (1 + waste %).
Worked example
A 12 × 10 ft slab at 4 inches deep has a base volume of about 1.48 cubic yards before waste.
How to use this calculator
- Choose slab, footing, or round column.
- Use finished inside form dimensions.
- Enter slab thickness in the selected length unit.
- Set the number of identical placements.
- Apply a waste allowance that reflects measured site conditions and supplier guidance.
Supported units
Feet, inches, meters, and centimeters for dimensions; results in cubic feet, cubic yards, and cubic meters.
Reference table
| Volume | Equivalent |
|---|---|
| 1 cubic yard | 27 cubic feet |
| 1 cubic yard | 0.7646 cubic meters |
| 1 cubic meter | 1.308 cubic yards |
Practical guidance
- Measure depth at several points.
- Confirm whether your supplier sells partial yards.
- Keep reinforcement volume in the estimate unless a specialist directs otherwise.
Assumptions and limitations
The calculation assumes uniform dimensions. Irregular excavation, compaction, spillage, subgrade variation, and supplier minimums may change the order quantity.
Methodology
Rectangular volume is length × width × depth. Circular-column volume is π × radius² × height. Quantity is applied before waste and unit conversion.
Read the complete calculation methodology and testing policy.
Sources and technical references
References support terminology, units, or practical constraints. They do not imply endorsement or project approval.
- NIST Special Publication 811 — Guide for the Use of the International System of UnitsReference for SI units, symbols, and conversion-factor practice.
- American Cement Association — concrete conversion factorsIndustry reference including cubic-foot, cubic-yard, and cubic-meter conversion factors.
Frequently asked questions
Should I add waste to concrete?
A modest allowance is common for uneven forms, spillage, and measurement variation.
What is the difference between cubic feet and cubic yards?
One cubic yard equals 27 cubic feet.
Can this size structural footings?
No. It estimates volume only; footing design must follow plans and local requirements.