In this paper, we take into account Lorentz’s relativistic mass and then derive formulas for the Planck length and the Planck time that are not dependent on any other constants. Thus we can find the Planck length, the Planck time, and also the speed of gravity, from gravitational observations without any knowledge of any physical constants. This is in strong contrast to what has been, and currently is, thought to be the case. Since we take into account relativistic mass, our formulas are also fully accurate for a strong gravitational field. We will claim general relativity theory cannot be fully precise in respect to strong gravitational fields. For example, general relativity theory leads to an imaginary time dilation factor when at the Planck length distance from a Planck mass, but when taking into account Lorentz’s relativistic mass, the time dilation works properly all the way down to, and including, the Planck length distance.