Designing beer recipes - 5 or 5.5 gallon batch question.

I see a lot of recipes on here billed as a 5.5 gallon batch, and Palmer recommends putting 5.5 gallons in your primary since some of the wort is going to be absorbed by the trub and yeast and you'll be left with 5 gallons of beer when all is said and done. I usually boil 6.5 gallons down to about 5.5 gallons myself for the same reason Palmer endorses.

So my question is do I use 5.5 or 5.0 gallons in all my recipe calculations? I guess I'm wondering if the 0.5 gallons absorbed by trub and yeast count as lost wort or just as dead space.

Thanks for the help guys.

Count it as 5.5. As thats the volume that you are putting in the fermenter. While you could and will lose the half gallon to loss, you might have more or less, but you need it to have more accurate calculations of your formulas.

It is lost wort. You can do some math over your next couple batches and calculate loss on your system. I.e. if you get 6.5 in the kettle, boil for an hour and are left w/ 5.5 gallons, then lose .5 gallons in trub and transfer, you are left w/ 5 gallons drinkable beer. I found on my system I rarely got that loss (I got more) so I would get closer to 7 gallons in the pot if I wanted 5 gallons to drink.