Concrete Calculator
Our free concrete calculator estimates the volume of concrete you need for any rectangular pour — slabs, footings, steps or walls. Enter the dimensions and get instant results in cubic yards and cubic metres, along with premix bag counts.
Select Bag Size
Results will show bags needed for your selected size
Imperial Bags (US/Canada)
Default: 80 lb (imperial) · 20 kg (metric)
How to Use This Calculator
- Choose Imperial or Metric units.
- Enter the length and width of the area.
- Enter the depth/thickness.
- Your concrete volume appears immediately, including bag counts and a +10% waste recommendation.
Concrete Volume Formula
Cubic Yards = Volume (ft³) ÷ 27
Cubic Metres = Volume (ft³) × 0.0283168
Concrete Ordering Tips
- Always order 10% more than calculated to cover waste and overrun.
- Ready-mix is cheaper per yard than bags for pours over 1 yd³.
- Most batch plants have a minimum order of 1 cubic yard.
- Have your forms set and subbase prepared before the truck arrives.
Frequently Asked Questions
How do I calculate concrete volume? +
Multiply length × width × depth. Convert all measurements to the same unit first (feet), then divide by 27 for cubic yards. Our calculator does this for you instantly.
What is the difference between concrete and cement? +
Cement is an ingredient in concrete. Concrete is made from cement, water, sand (fine aggregate), and gravel (coarse aggregate). The cement acts as the binding agent.
How many square feet does a yard of concrete cover? +
At 4 inches thick, 1 cubic yard covers 81 square feet. At 6 inches thick, it covers 54 square feet. At 3 inches thick, it covers 108 square feet.
How long does concrete take to set? +
Concrete typically sets enough to walk on within 24–48 hours, but reaches full design strength (as measured at 28 days) after about four weeks of curing.
Can I mix concrete by hand for large jobs? +
Hand mixing is practical for small pours under 0.5 cubic yards. For larger jobs, rent a mixer or order ready-mix concrete to ensure consistent quality and save time.