I was just experimenting with the 'Brew It!' tool on Brewers' Friend and the instructions say that for a 12 litre boil, I should add 8.8 litres to the kettle along with 5kg of dry malt extract which equates to a further 3.2 litres totaling 12L - my target volume.
I'm going to reasonably assume that Brewers' Friend knows it's stuff but I have always taken the boil volume to be the water only!
Have I been doing it wrong?
For the purposes of future brewing and consistency should I just adjust my recipe so the pre boil water volume reads 12L?