We show that the temperature coefficient of the resonant frequency of the tetragonal ceramics, tau(f), correlates to the measured tetragonality ratio (c/a). This is based on a previously established relation between c/a and the oxygen positional parameter it. As the c/a ratio approaches its ideal value, the value of it also approaches its ideal value and the distortion of the oxygen octahedral decreases, leading to an increase of tau(f) to a positive value. Theses relations were confirmed by experimental measurements using three dielectric compositions, with varying c/a ratio near ideal.