Hi @cazzlewazzle89
I meant the sum of all the branch lengths in the tree. If you are using Python, you could use the total_branch_length() function of the Phylo.BaseTree included in Biopython: https://biopython.org/docs/1.75/api/Bio.Phylo.BaseTree.html#Bio.Phylo.BaseTree.TreeMixin.total_branch_length
For the other normalisation method using the mean value, that will also work (https://www.sciencedirect.com/science/article/pii/S1931312818303172)
Best,
Aitor