Abstract The main target of this study is to investigate a simple way to extract the magnetic material hysteresis curve using a new numerical integration method. The most used method for extracting the hysteresis loop involves integrating the measured voltage signal through a capacitor. This method is a hardware and analogical integration which requires precise dimensioning of the integration capacitor. Moreover, it is imprecise for the nonsinusoidal voltage signal. In this paper, one has interested to all types of voltage signals (with and without harmonics). The proposed method allows to directly integrate all signal waveforms with a good accuracy and low cost materials and times. The method is implemented in OCTAVE open source. The experimental acquisition is carried out using a testing bench to measure the transformer's primary current and secondary voltage signals. The proposed method is first validated on the primitives of the nonsinusoidal usual signals such as triangle and square signals. Then it is applied to extract the hysteresis loop of single phase transformer. The area of hysteresis loop which gives the iron losses is compared to the measured one given by a Wattmeter for several voltages. The computed and measured iron losses are practically identical. Thus, the validation of the proposed approach is performed and the finding of this research may serve as an alternative technique to direct and fast determining the hysteresis loop with a good accuracy.