How to use it
- Enter the patio length and width in feet.
- Input the slab thickness in inches.
- Add the price per cubic yard of concrete.
- Click calculate to see cubic yards, bags, and estimated cost.
This calculator turns your patio dimensions into the exact numbers you need to order concrete. It takes length, width, thickness, and price per cubic yard, then instantly shows cubic yards, estimated cost, number of 80-lb bags, and total cubic feet. Why this matters: knowing your cubic yardage prevents over-ordering (wasting money) or under-ordering (delaying the job). The bag count uses the standard yield of 0.6 cubic feet per 80-lb bag, so you can choose between ready-mix and bagged concrete. For example, a 10x10 slab at 4 inches thick is about 1.23 cubic yards, 33.3 cubic feet, and roughly 56 bags — the calculator does this in seconds. Read the results as your shopping list: round up bags, confirm yards with your supplier, and use the cost estimate to set your budget. It's built for DIYers and pros alike.
Pro tips
- Add 10% waste allowance to your final cubic yards to cover spillage, uneven subgrade, or form errors.
- Always round bag counts up to the next whole bag — you can't order a fraction of a bag.
- When ordering ready-mix, round up to the nearest quarter yard; most suppliers charge for that amount anyway.
- Avoid the common mistake of forgetting thickness variations — measure low spots and account for extra depth.
Real-life examples
- Planning a new 12x16 backyard patio and need to budget for materials.
- Estimating concrete for a 4-foot-wide walkway around your house.
- Comparing ready-mix vs. bagged concrete cost for a DIY slab project.
Case study
Mark used the calculator for a 12x16 patio at 4 inches thick. It showed 2.37 cubic yards and 107 bags. Adding 10% waste, he ordered 2.6 cubic yards of ready-mix, saving $120 by avoiding overorder and completing the pour without a shortfall.