Brewer's Friend: creating new recipes/numbers don't make sense

[cayslayer]

I'm entering a clone recipe into Brewer's Friend for a 5 gal all grain batch.
So, my target going into the fermentor is set to 5 gallons.
This automatically calculates a boil size of 4.25 gallons.

Why, oh why, is my boil size lower that my fermentor size?
What am I missing here?

 

[flars]

Been a while since I looked at this recipe builder. Is there a cell to indicate full boil or partial boil?

 

[cayslayer]

Not that I can see. It has a dropdown menu for mash types but not boil.

 

[timeasterday]

Can you post a link to the recipe?

 

[cayslayer]

https://www.brewersfriend.com/homebrew/recipe/view/577346/uff-limesicle-clone

 

[flars]

Boil size is a volume that you enter. Five gallons in the fermentor plus losses due to boil off, grain absorption, etc. Click on the "?" next to boil size for the explanation. (It is Brewtoad that has the cell for partial or full boil.)

 

[timeasterday]

If you go under "Tools" then "Quick Water Requirements" you'll see the actual calculations. Looks like you need 6.99 gallons preboil. The boil size field is manually entered and I usually go back and adjust that after checking the quick water requirements.

 

[cayslayer]

That's why i felt so stupid; the explanation didn't make sense either.
Those sizes are already entered whenever I create a recipe, which made me think I was really missing something.
It feels counter-intuitive to select a 5 gallon 'into the fermentor' size and have trub/grain/boil off come off of that number, as opposed to adding it back in. My brain thinks of it like this:

5 gal target size + trub loss + boil off + grain absorb. = starting volume, right?
that puts you at, say 7.25 gal. (1 gallon each for boil off and grain, a quart for trub)

If it were 5 gallons going into the kettle, it makes more sense that the boil size would be smaller.
I'm probably not making much sense either. Might be having a super dyslexic moment here.

Anyway, thank you very much for your responses

 

[timeasterday]

My brain thinks of it like this:

5 gal target size + trub loss + boil off + grain absorb. = starting volume, right?
that puts you at, say 7.25 gal. (1 gallon each for boil off and grain, a quart for trub)

Yeah that's pretty much the formula (you also have to add in volume increases from sugar, but it's not much). Although BF is calculating 8.69 gallons total volume. You need to measure your boil off rate for your setup, if you haven't already. Grain absorption rate will vary depending on the process. I use 0.1 gal per pound of grain for my BIAB brews. Looks like BF is estimating a bit higher for you, so that's something to put in your equipment profile.