Calculator guide
Find ready-mix volume for a rectangular slab from finished dimensions. Use the explicitly labelled inputs below; rates, dimensions, and costs are assumptions, not live quotes.
Formula or method
Cubic yards = length in feet × width in feet × thickness in inches ÷ 12 ÷ 27. Apply overage before multiplying by price per cubic yard.
How to use this calculator
- Set Slab length (ft). The interface starts with 20; replace it with the value for your scenario.
- Set Slab width (ft). The interface starts with 12; replace it with the value for your scenario.
- Set Slab thickness (in). The interface starts with 4; replace it with the value for your scenario.
- Set Overage (%). The interface starts with 10; replace it with the value for your scenario.
- Set Price per cubic yard ($). The interface starts with 165; replace it with the value for your scenario.
- Compare the result with the worked example, then vary one assumption at a time so you can see what changes.
Worked example
Enter Slab length = 20 ft; Slab width = 12 ft; Slab thickness = 4 in; Overage = 10 %; Price per cubic yard = 165 $. With those assumptions, the calculator gives Concrete volume: 3.26 yd³; Order quantity: 3.3 yd³; Estimated ready-mix cost: $537.78; Formula: length × width × depth ÷ 324. These outputs are calculated from the same implementation as the interactive tool.
Understanding the result
In this example, Concrete volume is 3.26 yd³. Order quantity is 3.3 yd³. Verify measurements, manufacturer coverage, packaging, local code, and site conditions. Quantity and budget estimates do not certify structural or electrical safety.
Limitations and assumptions
- Verify measurements, manufacturer coverage, packaging, local code, and site conditions. Quantity and budget estimates do not certify structural or electrical safety.
- The worked example demonstrates the stated assumptions, not a recommendation about your personal circumstances.
Frequently asked questions
Which inputs should I check first?
For Concrete Calculator, check Slab length, Slab width, Slab thickness, Overage, Price per cubic yard. Keep the displayed units and select options consistent; do not treat default values as recommendations.
Why might my result differ from another tool?
Compare the other tool's concrete calculator method, input units, rounding and assumptions. A matching title does not guarantee that both tools answer the same question.
Does a linked reference certify this result?
No. A reference can explain a formula or provide background for Concrete Calculator, but it does not endorse this website, validate personal inputs or establish professional suitability.
Sources
Educational and planning information only. Sources are attributed background or formula references, not endorsements. Verify consequential decisions with an appropriate qualified professional.