Concrete Calculator
Calculate the exact amount of concrete you need for slabs, footings, walls, and columns. Enter your dimensions and get results in cubic yards, cubic feet, and bag counts.
Input Values
Results
How to Use This Calculator
How to Use the Concrete Calculator
- **Measure the Length** — Use a tape measure to find the longest dimension of the area you plan to pour. Enter this value in feet.
- **Measure the Width** — Measure the dimension perpendicular to the length. Enter this value in feet.
- **Determine the Depth** — Decide the thickness of your concrete slab. Standard thickness is 4 inches for patios and walkways, 5–6 inches for driveways. Enter this value in inches.
- **Read the Results** — The calculator shows cubic yards (for ordering ready-mix), cubic feet, and bag counts for both 80 lb and 60 lb pre-mixed concrete.
- **Order Extra** — Add 5–10% to your total to account for waste, uneven ground, and spillage.
Tips for Accurate Measurements - Measure in multiple spots if the ground is uneven and use the deepest measurement. - For irregular shapes, break the area into rectangles, calculate each separately, and add them together. - Always double-check measurements before ordering.
Tips & Best Practices
- ✓Set up solid forms before pouring to ensure even depth and straight edges.
- ✓Wet the ground and forms before pouring to prevent rapid moisture loss from the concrete.
- ✓Pour concrete in temperatures between 50°F and 85°F for best curing results.
- ✓Use a screed board to level the surface immediately after pouring, then finish with a float.
- ✓Cure concrete for at least 7 days by keeping it moist — cover with plastic sheeting or use a curing compound.
Frequently Asked Questions
How many bags of concrete do I need for a 10x10 slab?
For a 10×10 ft slab at 4 inches deep, you need about 1.23 cubic yards of concrete, which equals roughly 56 bags of 80 lb pre-mixed concrete or 74 bags of 60 lb concrete.
How thick should a concrete slab be?
A standard concrete slab for a patio or sidewalk should be 4 inches thick. Driveways typically require 5–6 inches, and garage floors need at least 6 inches. For heavy loads, consider 8 inches or more.
Should I order extra concrete?
Yes, it is recommended to order 5–10% more concrete than calculated to account for uneven ground, spillage, and form irregularities. Running short during a pour can compromise the structural integrity of the slab.
What is the difference between 80 lb and 60 lb bags?
80 lb bags yield about 0.6 cubic feet of concrete each and are more cost-effective per volume. 60 lb bags yield about 0.45 cubic feet each and are easier to handle. Choose based on your physical comfort and project scale.
How do I convert cubic feet to cubic yards?
Divide the number of cubic feet by 27 to get cubic yards. For example, 54 cubic feet equals 2 cubic yards. This calculator performs the conversion automatically.