What is the classification accuracy of a random classifier? I have a build a classification model using machine learning technique (SVM). I want to compare the classification accuracy of my model with a random classifier. My data set contains only two classes(1 or 0). The ratio of 1 and 0 instances are 35% and 65%. That means, 35% instances belong to 1 and 65% belong to 0 class. In that case, what will be the classification accuracy of random classifier (Random Guess)?
The equation of the classification accuracy for a random classifier (Random guess) is as follows:

Accuracy = 1/k (here k is the number of classes).
In your case, the value of k is 2.

So, the classification accuracy of the random classifier in your case is 1/2 = 50%