The circumference's the distance around a closed curve. Circumference's a special perimeter. Circumference of a circle The circumference of a circle's the length around it. The circumference of a circle can be calculated from its diameter using the formula: » c=picdot, results with different ellipticities can be found and compared: b Pr Ramanujan-#2 Ramanujan-#1 Muir 9975 9966 9950 9900 9000 8000 7500 6667 5000 3333 2500… (More on Circumference)