Determining your harmonic frequency requires first identifying the foundational fundamental frequency of the wave, string, acoustic tone, or electrical signal in question. Once the fundamental frequency value is established, you find any specific harmonic by multiplying that baseline figure by the integer order of the desired harmonic. For example, if you are looking for the second harmonic of a 100 Hertz tone, you multiply 100 by 2 to get 200 Hertz. In experimental settings, engineers utilize digital spectrum analyzers, Fourier transform software, or oscilloscope FFT functions to visualize and measure these exact harmonic frequency peaks directly.