How to use this calculator
Enter length and width in one selected unit, then depth in its own unit. Add an extra material percentage if appropriate. Read the order estimate in cubic yards, feet or meters.
The math behind it
Base volume = length × width × depth (converted to meters) Volume with allowance = base volume × (1 + allowance ÷ 100) Cubic yards = cubic meters ÷ 0.9144³
A worked example
A 10 ft × 12 ft slab at 4 in thick has 40 ft³ of concrete. With 10% allowance, that becomes 44 ft³, or about 1.62963 yd³.
Assumptions & precision
Dimensions must be positive. Extra material allowance is a nonnegative percentage added once to geometric volume. Exact international foot = 0.3048 m; yard = 0.9144 m. Rectangular geometry only. Actual waste, settling, excavation and supplier increments vary. Unrounded intermediate values; results display up to 6 decimal places. Magnitudes above 10¹⁵ are rejected. This is volume estimation, not structural design or a mix-strength specification.
A common question
Does this calculate bags of concrete?
No. Bag yield varies by product and water/mix instructions. Divide the required volume by the manufacturer’s finished-volume yield and round up.