Concrete Calculator & Estimator
Planning a concrete pour means knowing exactly how much material to order. This calculator helps you figure out the precise volume and the number of premix bags you need for your project.
Last updated: February 2026
How to Use This Calculator
- Select your project shape from the tabs above the diagram.
- Look at the diagram to match up your measurements.
- Enter your dimensions and select the right units.
- Click "Calculate Volume" to get your total yards, meters, and bag estimates.
About the Concrete Estimator
Why This Tool Exists
Buying too much concrete wastes money, and running out mid-pour ruins the job. We built this tool to take the guesswork out of ordering materials. It gives you reliable estimates so you can tackle your concrete projects with confidence.
When Should You Use This Tool?
This calculator is helpful for several common construction tasks:
- Pouring a new patio, driveway, or sidewalk.
- Setting fence posts or deck footings in cylindrical holes.
- Building concrete steps for a porch or landscape feature.
- Estimating the number of 60lb or 80lb bags for a weekend DIY job.
- Calculating continuous curb and gutter volumes for street edges.
How the Tool Works
You just select the shape of your project, like a flat slab or a round column. Enter your measurements in feet, inches, or meters. The calculator runs the geometry to find the total volume and translates that into cubic yards, cubic meters, and standard bag sizes. It also provides an estimated total weight.
Limitations and Accuracy
This tool provides mathematical estimates based on perfect shapes. Ground surfaces are rarely perfectly level, and forms can bow slightly during a pour. It is a good idea to order 5 to 10 percent extra to cover uneven subgrades and typical job site waste.
Frequently Asked Questions
How many bags of concrete make a cubic yard?
You will typically need 45 bags if you buy the 80lb size, or 60 bags if you buy the 60lb size to make one cubic yard.
How do I figure out how much concrete I need for a flat slab?
Measure your length, width, and thickness. Multiply these three numbers to find the total volume. If you measure in feet, divide that final number by 27 to get cubic yards.
How heavy is a yard of concrete?
A standard cubic yard of wet concrete weighs right around 4,000 pounds or roughly 1,800 kilograms.
Can I mix different measurement units in the calculator?
Yes, you can enter your length in feet and your thickness in inches. The tool converts everything to a standard volume automatically.