# How to Calculate a Round Concrete Patio

Save

Calculating the amount of concrete needed to pour a patio requires the use of a mathematical formula. Guessing the amount of concrete for your round patio will result in over-ordering material or falling short of the material needed during the concrete pour. Falling short will result in a patio weak from a thin slab or low spots in the finished patio. The extra money spent on over-ordered concrete will cause your project to run over budget.

### Things You'll Need

• Calculator
• Notebook
• Pencil
• Enter the diameter of your patio in the calculator.

• Divide the diameter by two to find the radius.

• Press the "times" and then the "equals" button to square the radius. For example, if your patio is 12-feet in diameter, dividing by two will result in six. Pressing, "times" then "equals" will yield the number 36 (radius squared.)

• Multiply the radius squared amount (36 in the example) by Pi (3.142) and then multiply that number by the depth of your slab.

• Write that number in a notebook. Clear the calculator.

• Divide the depth of your concrete by 12. For example, a 4-inch thick slab is 4 divided by 12, which equals 0.33.

• Multiply the saved number by the number you obtained in Step 6. Continuing with the example, the number written, 113.112 multiplied by 0.33 equals 37.33.

• ### Other People Are Reading

• Finish the equation by dividing the result from Step 7 by one cubic-yard (27). Finishing the example, 37.33 divided by 27 equals 1.38, the cubic-yards of concrete needed to pour a patio 12 feet in diameter, 4-inches thick.

## Tips & Warnings

• Add 10 percent to the final number before you order concrete; it's better to have slightly too much rather than not enough.

## References

• Photo Credit concrete factory image by dinostock from Fotolia.com
Promoted By Zergnet

## Related Searches

Check It Out

### 22 DIY Ways to Update Your Home on a Small Budget

M
Is DIY in your DNA? Become part of our maker community.