Spike's Calculators

# Circular Slab Concrete Calculator

Calculate the amount of concrete needed in cubic feet and cubic yards for a slab in the shape of a circle.

To calculate the concrete volume needed for this type of slab, you need to know the circle's diameter and the depth of this slab..

##### Formulas
Area
`A = π * D²  ÷ 4`

Perimeter
`P = π * D`

Volume
`V = π * D² ÷ 4 * (d ÷ 12)`

```where A is the area in square feet, p = 3.14159265358979, D = diameter of circle
P is the perimeter in lineal feet, p = 3.14159265358979, D = diameter of circle
V is the volume in cubic feet, p = 3.14159265358979, D = diameter of circle, d = depth of slab in inches ÷ 12 converting this to feet```

```To convert cubic feet to cubic yards, multiply cubic feet * 0.037037037037037
To convert cubic feet to cubic metres, multiply cubic feet * 0.028316846592
To convert cubic yards to cubic metres, multiply cubic yards * 0.764554857984```
##### Example calculation
```Diameter of slab = 12 feet
depth of slab = 4 inches```

Area
Calculate the area in square feet using the Area formula;
`3.14159 * 12² ÷ 4 = 3.14159 * 144 ÷ 4 = 113.1 (rounded to one digit)`
`The area of the slab is 113.1 square feet`

Perimeter
Calculate the circumference (perimeter) of this slab using the Perimeter formula;
`3.14159 * 12 = 37.6 (rounded to one digit)`
`This slab has a circumference of 37.7 feet`

Volume
Calculate the amount of concrete you need for this slab using the Volume formula;
`3.14159 * 12² ÷ 4 * (4 ÷ 12 ) = 3.14159 * 144 ÷ 4 * 0.333 = 37.7 (rounded to one digit)`
`The volume of this slab is 37.7 cubic feet`

### Circular Concrete Slab

Diameter ft in
Depth in

 Square Footage of Slab ft² Perimeter of Slab ft Amount of Concrete Needed in: Cubic Feet ft ³ Cubic Yards yd ³ Cubic Metres m³

#### Calculation

1. enter the diameter of the slab in feet and inches
2. slab depth in inches

#### Results

1. the area of the slab calculated in square feet
2. the circumference (perimeter) of the slab in feet
3. amount of concrete needed in cubic feet
4. concrete needed in cubic yards
5. concrete needed in cubic metres

### When Ordering Concrete

This concrete calculator will help you in estimating the amount of concrete needed for your project. The amount given as needed does not include any waste. Depending on your job, we recommend adding anywhere from an extra 4% to 10% to your concrete required calculation to make sure you have enough concrete to finish the job. Ask when ordering the concrete. They will be able to give you a good idea of what is needed.