Pouring a new patio or driveway? Running out of concrete halfway through a job is an absolute nightmare. Use our free concrete calculator to find exactly how much material you need before you start mixing. Whether you are ordering a massive ready-mix truck by the cubic yard or just buying bags from Home Depot, this tool runs the complex volume math instantly.
Total Cubic Yards Needed
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80lb Bags Needed
0 Bags
60lb Bags Needed
0 Bags
*Results include a mandatory 10% waste/spillage buffer.
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How to Use This Concrete Yardage Calculator
Finding your exact concrete volume is straightforward. First, take a tape measure and find the total length and width of the slab you are pouring in feet. If you have a complex shape, break it down into smaller squares and run the calculator multiple times.
Next, determine your thickness. A standard backyard patio or sidewalk is usually poured at 4 inches thick. A heavy-duty driveway meant to hold trucks should be at least 6 inches thick. Enter these numbers and hit calculate. The tool automatically adds a 10% safety margin to ensure you do not run short.
The Concrete Volume Math Explained
Concrete is heavily regulated volume math. It is always ordered by the "cubic yard." A single cubic yard is a massive block of concrete that measures exactly 3 feet long by 3 feet wide by 3 feet deep. This means there are 27 cubic feet in a single cubic yard.
To do the math manually, you convert your slab's thickness from inches into feet (e.g., 4 inches divided by 12 equals 0.33 feet). You then multiply the Length × Width × Depth to find the total cubic feet. Finally, you divide that massive number by 27 to find the exact cubic yardage required from the ready-mix plant.
Concrete Calculator Example
Let's pretend you are pouring a brand new 10-foot by 10-foot patio in your backyard. You want it to be a standard 4 inches thick. Using our concrete calculator, we find the baseline volume is 1.23 cubic yards.
Because the dirt underneath is never perfectly level, our calculator automatically tacks on a 10% safety margin, bringing the total order to 1.36 cubic yards. If you plan to mix this by hand (which will break your back), the tool shows you will need to buy exactly sixty-two 80-pound bags from the hardware store to get the job done.
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Tips for Pouring Concrete in 2026
Always over-order: If you order exactly 2.0 yards of concrete and the forms bow outwards by half an inch, you will come up short. Always order an extra half-yard or add a 10% margin. Coming up short ruins the entire pour.
Truck vs Bags: If your project requires more than 1.5 cubic yards, call a ready-mix truck. Mixing 70 bags of concrete by hand in a wheelbarrow will completely destroy your shoulders.
Prep the subgrade: Concrete is only as strong as the dirt beneath it. Ensure you have a highly compacted gravel base before you pour a single drop of mud.
Use wire mesh: Concrete has massive compressive strength but terrible tensile strength. Always add wire mesh or rebar to your 4-inch slabs to prevent them from cracking and pulling apart.
Frequently Asked Questions
How do you calculate concrete yardage?
To calculate concrete yardage, find the volume of your slab in cubic feet (Length in feet × Width in feet × Depth in feet) and then divide that number by 27 to get cubic yards.
How many bags of concrete make a yard?
It takes exactly forty-five 80-pound bags of concrete, or sixty 60-pound bags of concrete, to make one single cubic yard of concrete.
Why do I need to order extra concrete?
You should always add a 10% waste factor to your concrete order to account for uneven subgrades, forms bowing outward, and spillage. Coming up short on a pour is a disaster.
Is concrete measured in yards or feet?
Ready-mix concrete from a truck is always sold and measured in cubic yards. However, dry bags from the hardware store are usually measured by weight (pounds) or cubic feet.
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Don't run out of mud halfway through the job. Scroll up and run your exact dimensions through our free concrete calculator before you buy.