Also, since you are using your side measurement only to determine your border length, there is no easing/stretching involved. In many cases folks measure their quilts both sides and center to make sure it is square. If there is any discrepancy in those measurements, you can take an average of the 3 measurements to help 'square up' the quilt with the borders. In that case, your border fabric may not be the same length as your quilt, hence the need for easing/stretching your border fabric.