Last updated October 13, 2026 · Report an error
Ordering the wrong amount of concrete means either a costly extra delivery or bags of leftover mix — getting the volume right up front avoids both.
This calculator finds the cubic yards of concrete needed for a slab, footing, or patio, along with how many pre-mixed bags to buy.
How it works
Enter the length, width, and thickness of the area you're pouring, and how many identical sections you need. The calculator finds the total volume in cubic feet and cubic yards, and estimates how many 60 lb or 80 lb bags of pre-mixed concrete that volume requires.
- Enter length (ft).
- Enter width (ft).
- Enter thickness (inches).
- Enter number of identical sections.
- Click Calculate to see your results.
Examples
A 10×10 ft patio slab
A 10 ft by 10 ft slab poured 4 inches thick needs about 1.23 cubic yards of concrete — roughly 75 bags at 60 lb each, or 56 bags at 80 lb each.
Who should use it
- Planning a DIY patio, walkway, or shed foundation pour.
- Estimating material costs for a small concrete project before ordering supplies.
Industry applications
- Residential construction and home improvement
- DIY landscaping and hardscaping projects
Advantages
- Calculates both cubic yards (for ready-mix orders) and bag counts (for bagged concrete) in one step.
- Supports multiple identical sections in a single calculation.
Limitations
- Assumes a simple rectangular pour — irregular shapes need to be broken into rectangular sections and calculated separately.
Common mistakes to avoid
- Forgetting to convert thickness from inches to feet before calculating volume — this calculator handles that conversion automatically.
- Not accounting for an ready-mix truck's minimum order size, which can make small pours more cost-effective with bagged concrete instead.
Best practices
- For pours over about 1 cubic yard, compare the cost and effort of bagged concrete against ordering ready-mix delivery, which is often more economical past that point.
Tips
- Measure twice before ordering — concrete is heavy and expensive to over-order, and running short mid-pour can compromise the finished slab.