Measurements of vapor bubble growth were made in microgravity using R-113 with transient heating at a flat surface, and comparisons made with a combination of two one-dimensional spherical models; an initially uniform superheat model, using the highest temperature at nucleation, denoted as the upper bound of growth, while the second model uses the non-uniform temperature distribution at nucleation as the initial condition surrounding the critical size vapor bubble, denoted as the lower bound. A bubble growth fraction is introduced, related to the upper and lower bounds, and provides a simple index to describe the vapor bubble growth.