The distribution in energy of Johnson noise pulses (random thermal voltages in a resistor) is derived and checked against pulse‐height measurements made with a linear amplifier and electronic counter. The following parameters are determined from the distribution function: (1) time of flight associated with a Lorentz mean free path, (2) the number of electrons which produce a pulse of a given height, and (3) the potential an electron falls through in a Lorentz mean free path.