Concrete Volume
Calculate the concrete needed for a slab in cubic yards.
About Concrete Volume
A slab's volume is length times width times thickness converted to feet. Dividing cubic feet by 27 gives cubic yards, and premixed bags convert to small projects. Ordering a ready-mix truck too small leaves you short, while too much concrete cannot be returned, so matching the true volume matters.
Formula
Concrete Volume
Cubic yards = length x width x (thickness/12) / 27
- bags
- Premixed bags each yield a fraction of a cubic foot
Worked example
With the default values below, Concrete Volume returns Volume of 40.0. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Slab lengthminimum 0 ft
- 12 ft
- Slab widthminimum 0 ft
- 10 ft
- Slab thicknessminimum 0 inches
- 4 inches
Results
- Volume
- 40.0 cu ft
- Volume
- 1.48 cu yd
- 60 lb Bags
- 89
- 80 lb Bags
- 67
Step by step
- 1Values used
- 2Concrete Volume
- 3Volume= 40.0 cu ft
- 4Volume= 1.48 cu yd
- 560 lb Bags= 89
- 680 lb Bags= 67
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Concrete Volume calculated?
Cubic yards = length x width x (thickness/12) / 27 A slab's volume is length times width times thickness converted to feet. Dividing cubic feet by 27 gives cubic yards, and premixed bags convert to small projects.
Why does Concrete Volume matter?
Ordering a ready-mix truck too small leaves you short, while too much concrete cannot be returned, so matching the true volume matters.
What values do I need to enter?
This calculator takes 3 inputs: Slab length, Slab width, Slab thickness. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.