By coupling an analog computer to a conventional high‐sensitivity electron spin resonance (ESR) spectrometer, the total absorption of ESR spectra, which is essentially proportional to the total number of resonances present, is obtained automatically with a typical standard error of 8% for uncorrected data or 2% for simply corrected data. Other considerations inherent in the combination of such equipment are also discussed. An experimental check of the linear dependence of first moment of the usual spectrometer output on field modulation is given.