Determining the Ratio of Circumference to Diameter of a Circle In determining the ratio of the circumference to the diameter I began by measuring the diameter of one of the si objects which contained circles, then using a string, I wrapped the string around the circle and compared the length of the string, which measured the circumference, to a meter stick. With this method I measured all of the six circles. After I had this data, I went back and rechecked the circumference with a tape measure, which allowed me to make a more accurate measure of the objects circumferences by taking away some of t