Abstract
Research on the perimeter of an ellipse has so far only found approximations. This occurs because the integral of the perimeter of an ellipse does not have an anti-derivative. Therefore, this study aims to find a new definite integral for the perimeter of an ellipse that has an anti-derivative. This study observed the relationship between the intersection of an elliptical cylinder, which results in a circle, and the perimeter of the base of the elliptical cylinder. This study found a new definite integral to obtain the exact formula for the perimeter of an ellipse, which can be solved analytically.