How will you find the right K for K-means?

To find the optimal value for k , you can use the elbow method or silhouette method

In cluster analysis, the elbow method is a heuristic used in determining the number of clusters in a data set . The method consists of plotting the explained variation as a function of the number of clusters, and picking the elbow of the curve as the number of clusters to use.

The silhouette Method is a method to find the optimal number of clusters and interpretation and validation of consistency within clusters of data . The silhouette method computes silhouette coefficients of each point that measure how much a point is similar to its own cluster compared to other clusters.