How to use it
- Enter the length in feet.
- Enter the width in feet.
- Enter the thickness in inches.
- Press Calculate to see cubic yards, bags, and cubic feet.
This calculator takes three simple measurements — length, width, and thickness — and turns them into the exact concrete volume you need. You get cubic yards, cubic feet, and the number of standard 80-lb bags to order. That number matters because ready-mix concrete is sold by the cubic yard, while bagged concrete is sold by the bag. The calculator uses the standard yield of 0.6 cubic feet per 80-lb bag, so your bag count reflects real coverage. Read the cubic yards value when ordering from a ready-mix supplier, and read the bags value when picking up bags from the store. If the bag count looks like a fraction, round up to the next whole bag — and always consider adding a small waste allowance. Whether you're building a patio, footing, or walkway, this tool gives you a concrete number before you spend a dollar.
Pro tips
- Add 5–10% for waste, spillage, or uneven subgrade.
- Round bag count up to the nearest full bag — never order a fractional bag.
- For large pours, compare bag cost vs ready-mix; over about 1 cubic yard, ready-mix may be cheaper.
- Measure thickness in several spots; a half-inch difference changes the bag count more than you'd think.
Real-life examples
- Pouring a 10x12 patio slab at 4 inches thick.
- Setting fence posts with tube forms.
- Repairing a driveway section with bagged concrete.
Case study
Maya needed a 10x12 slab at 4 in thick. She entered numbers and got 1.48 cu yd, about 67 bags. She ordered 72 with waste, finished with enough mix and saved a second store run.