Ah. Sorry, I haven't answered this. I got so caught up answering the other stuff.
The short end of it is that I don't know. I don't have a tool to measure his weight accurately. And while this may be the most accurate way to measure the proper food, going by the girth and not feeding them anything larger than the widest part of their body is actually a good method that I've seen tested and done by successful BP owners with content snakes.