How to use it
- Enter the length of the area in feet.
- Enter the width of the area in feet.
- Enter the thickness of the concrete in inches.
- Click Calculate to see cubic yards, bags, and cubic feet.
This calculator tells you exactly how much concrete you need for any slab, pad, or footing. You enter the length, width, and thickness, and it instantly shows the volume in cubic yards, the number of 80-lb bags, and the total cubic feet. That matters because ordering too little means extra trips and cold joints; ordering too much means wasted money and hard-to-dispose leftovers. Read the cubic yards line when ordering ready-mix from a plant. Read the bags line when you're mixing by hand on site. Read the cubic feet line when you're comparing small batches or using a mixer. The calculator uses the standard yield for an 80-lb bag: 0.6 cubic feet. No guesswork, no math errors, and no short pours. Just enter your three numbers and get a concrete answer in seconds.
Pro tips
- Add 10% waste to your total to cover spillage, uneven subgrade, or slight over-dig.
- Round bag counts up to the next full bag—you can't buy a partial bag, and leftover dry mix stores fine.
- For large pours, order ready-mix by the cubic yard and round up to the nearest quarter yard so the truck doesn't run short.
- Don't forget to convert thickness to feet mentally—this calculator does it for you, but double-check you entered inches, not feet.
Real-life examples
- Planning a 10x12 ft patio slab and need to know how many 80-lb bags to buy.
- Estimating concrete for a 4-inch-thick garage floor before calling the ready-mix plant.
- Figuring out the concrete needed for a small shed foundation or walkway without overordering.
Case study
Mark needed a 10x12 ft patio at 4 inches thick. He entered the numbers and got 1.48 cubic yards and 67 bags. He ordered 2 cubic yards of ready-mix with waste included, finished the pour in one day, and avoided a second delivery fee.