A method for determining mechanical power dissipation in a vibratory system, assuming the system is linear time-invariant and steady-state. The method includes the steps of identifying connection points between the vibratory system and components outside the vibratory system. The acceleration is measured at each connection point in a windowed time domain and the force at each connection point is also determined for the windowed time domain. The time domain values are converted into the frequency domain values by the fast Fourier transform, and the frequency domain acceleration values are converted to velocity values. The power dissipation of the vibratory system then equals the summation of one half of the power flow into the vibratory system. Here, each power flow is one half of the real part of the product of complex-conjugated velocity times force at the connection point in the frequency domain for each time window.