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
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)