Spike's Calculators

# Circle

Calculate the area and perimeter (circumference) of a circle. This calculator uses feet for measurements.

Circle = a round shape.

### Circle Area and Perimeter

Diameter ft in n
d
Decimal Precision

#### Results:

###### Area of the Circle
Decimal Square Feet ft²
Square Feet ft² in²
Decimal Square Inches in²
Square Inches in²
Square Metres
###### Perimeter of the Circle
Decimal Feet ft
Feet ft in
Decimal Inches in
Inches in
Metres m

#### Calculation

1. the diameter in feet and or inches and, if needed, in a fraction of an inch
2. decimal precision, the number of digits after the decimal point

#### Results

1. the area of the circle in decimal square feet
2. area in square feet and inches
3. the area in decimal square inches
4. the area in square inches
5. the area in square metres
6. the perimeter of the circle in decimal feet
7. the perimeter in lineal feet and inches
8. the perimeter in decimal inches
9. the perimeter in inches
10. the perimeter in metres
##### Formula
```A = 𝝅/4D²
P = 𝝅D
where A is the area of the circle
𝝅= 3.14159265
D the diameter
P  the circumference of the circle
```

##### Conversions
```one square foot ( ft²) = 144 square inches (in²)
one square inch (in²) = 0.00694444444444443 square feet (ft²)
one square foot ( ft²) = 0.09290304 square metres (m²)
square inch (in²) = 0.00064516 square metres (m²)
```