In the current era of digitalization, there are so many applications of digital devices for daily necessities even for medical demand as well. One of them is the use of a digital blood pressure device which has advantages such as being easy to read and understand, small, easy to carry everywhere and relatively cheap in price. However, the problem is how accurate the device is when compared to analog/conventional devices whose accuracy has so far been no doubt. The Goal of this this design is knowing the accuracy of the measurement instrument, in this case as blood measurements instrument using the OMP and evaluation metric with data sampling size respectively K 128, K 64 K 32 and K 16, for assessing which data size having better accuracy. Keywords : Digital blood pressure, orthogonal matching pursuit (OMP), gaussian transform, wavelet transform, evaluation metrics.