In the user manual of velvet, http://www.ebi.ac.uk/~zerbino/velvet/Manual.pdf, there is a section:
4.2.2 The stats.txt file
This file is a simple tabbed-delimited description of the nodes. The column names are pretty much self-explanatory. Note however that node lengths are given in k-mers. To obtain the length in nucleotides of each node you simply need to add k − 1, where k is the word-length used in velveth.
I don't understand the paragraph. Let's say k==10, each node in the graph would have a length of 10. Why do we have to add k-1 to convert it? The length in nucleotides should also be k! In my example, each node would have a length in nucleotides of 10 (==k).