Mark your starting point. Place a ruler on one edge of the figure; replace the ruler with a tape measure for large objects. Align the zero calibration mark of the ruler to your starting point.
Measure the length of the edge; repeat the process to get accurate measurements. Record the measurements.
Repeat the procedure on all the edges of the figure and record all the observations.
Add up all the measurements recorded to get the perimeter.
Tie a knot on a string and place it on the object. Take the string round the figure up to the knot and mark the end.
Place the knot on the zero mark and stretch the string across the ruler up to the marked point.
Record the observations up to the marked point on the string to obtain the perimeter refer to the perimeter as circumference for round objects.
Replace the above with a mathematical formula for regular circles. Measure the distance between two points across the circle and record it as diameter abbreviated as D. Divide the diameter into two to get the radius to calculate the circumference with the formula 2πr; r symbolizes the radius or the formula πD with D symbolizing diameter. Diameter is also two times the radius and π equals 22/7 or 3.142.