Spike's Calculators

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

Circle = a round shape.

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

- the area of the circle in decimal square feet
- area in square feet and inches
- the area in decimal square inches
- the area in square inches
- the area in square metres
- the perimeter of the circle in decimal feet
- the perimeter in lineal feet and inches
- the perimeter in decimal inches
- the perimeter in inches
- the perimeter in metres

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

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)