I am building up on this video by Kieran Borovac. I will provide forward (from SI, labeled F) and backward (to SI, labeled B) matrices for each system, where the rows represent SI values and columns the corresponding system values. The rows in the backward matrices represent SI units: s,m,kg,A,K,cd,mol, in forward matrices, these are represented by columns. The units are represented by column vectors and are multiplied with the matrix for conversion.
To convert values, set the calculator to forward transformation (SI → [system]). To convert from the selected system to SI, multiply by the units and to convert from SI to the selected system divide by the units.