Spike's Calculators

Calculate the area and perimeter of a donut shape. This calculator uses feet and or inches for measurements

Donut = a circle with a smaller circle centred inside

- outer diameter in feet and or inches
- inner diameter in feet and or inches
- decimal precision, the number of digits after the decimal point

- the inner area in square feet
- total area (donut area plus inner area) in square feet and inches
- the area of the donut in square feet
- the area in decimal square inches
- the area in square inches
- the area in square metres
- the outer perimeter of the donut in decimal feet
- the outer perimeter in lineal feet and inches
- the outer perimeter in decimal inches
- the outer perimeter in inches
- the outer perimeter in metres
- the inner perimeter of the donut in decimal feet
- the inner perimeter in lineal feet and inches
- the inner perimeter in decimal inches
- the inner perimeter in inches
- the inner perimeter in metres

A = ta-ti ta = 𝛑D² ti = 𝛑d² 𝛑 = 3.14159265 PO = 𝛑D PI = 𝛑d PO the outer perimeter of the donut PI the inner perimeter of the donut

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)