Abstract: Recently, Machine learning algorithms, such as neural network, have made a great progress and are widely used in image recognition, data searching and finance analysis field. The energy consumption of machine learning algorithms becomes critical with more complex issues and higher data dimensionality. Because of the inherent error-resilience of machine learning algorithms, approximate computing techniques, which trade the accuracy of results for energy savings, are applied to save energy consumption of these algorithms by many researchers. We observe that most works are dedicated to leverage the error-resilience of certain algorithm while they ignore the difference of error-resilience among different algorithms. Understanding the difference on “approximatability” of different algorithms is very essential because when the approximate computing techniques are applied, approximatability can help the classification tasks choose the best algorithms to achieve the most energy savings. Therefore, we choose 3 common supervised learning algorithms, that is, SVM, random forest (RF) and neural network (NN), and evaluate their approximatibility targeted to different kinds of energy consumption. Meanwhile, we also design several metrics such as memory storage contamination sensitivity, memory access contamination sensitivity and energy diversity to quantify the difference on approximatability of learning algorithms. The conclusion from evaluation will assist in choosing the appropriate learning algorithms when the classification applications apply approximate computing techniques.