To normalize the time, you would have to base the size on the center of the circle to the furthest corner. You could probably change the timeScale, but if you're going that far into calculations, you might as well just set the correct size. All the circles here will finish at the same time.     See the Pen PdZQrL by osublake (@osublake) on CodePen       There's lot of uses in trigonometry. The relationship is like this.