Your result
How this calculation works
Volume = length × width × thickness after unit conversion. Required volume = base volume × (1 + waste percentage ÷ 100).
Calculate a rectangular slab from length, width, and thickness. Metric uses meters and centimeters; US units use feet and inches.
How to use this calculator
- Enter or choose measurement system.
- Enter or choose length (m or ft).
- Enter or choose width (m or ft).
- Enter or choose thickness (cm or inches).
- Enter or choose extra allowance (%).
- Select Calculate and review the result and assumptions.
Worked example
A 4 m by 3 m slab at 10 cm thickness is 1.2 m³. Adding 10% waste gives 1.32 m³.
Assumptions and limitations
Volume estimate only, not a structural design, concrete mix specification, price quote, or order guarantee. Verify measurements and supplier requirements.
Frequently asked questions
Does this calculate cost?
No. Material prices, delivery, labor, reinforcement, and site preparation vary and are not included.
Is the waste allowance a recommendation?
No. It is an editable assumption. Confirm the appropriate order quantity with your supplier.