The article focuses on Lemaître's Limit, a theoretical proof from Belgian scientist and mathematician George Lemaître for his 1927 doctoral thesis in astronomy, which indicates that the maximum spherical radius of the Universe can be calculated from first principles to be 14.2 billion light-years. It states that the calculation is based on his dynamic-equilibrium theory of the Universe. Moreover, his theory is recognized as a founding father of Big Bang cosmology.