I am planning on using about 2.5 lbs. of unmalted spelt in my upcoming saison. Does anyone have an idea on how to determine the extract potential of unmalted spelt, or any unmalted grain for that matter?
I will be using whole spelt berries. I plan on milling them along with the rest of the grist.
I realize I should learn how to determine this without relying on brewing software… Especially since not every grain is accounted for in the various software programs.
The only way I could think of would be to do a small test mash, 50/50 spelt and two-row. You would need to do a 100% two-row mash with the same equipment first, to determine what your expected efficiency would be.
In this particular case, I bet you could get really close by assuming it’s the same as raw wheat.
I use spelt quite often both in breads and beers. I’ve adapted the reference of 8.00°P (pppg; dry basis) based upon 74% efficiency on my mash system and that’s utilizing a “cereal-type” mash schedule. I can merely offer my number as a starting reference, as you have to figure out what works best on your particular system. Good luck with your saison! 
Um. Okay. I willingly admit a complete lack of understanding of your information. ??? ;D
I am not very handy with plato and unsure of what pppg stands for. Something parts per gallon?
My own system gets 81% average efficiency.
Admittedly, I have only done one cereal mash. That was with quinoa. I just cooked it as if I were going to eat it then added it to the mash. I think I guessed with that what I would get extract wise. It worked out fine but I would prefer to understand what I am doing! :
ppppg = points per pound per gallon = point-gal/lb
The quick and dirty Plato to SG conversion is to multiply by four. (Here’s the more accurate formula.) So 8°P is about 1.032. One pound of whatever, into one gallon of wort, will give a gravity of 1.032. This is the most common way for homebrewers to express extract potential; see for example this chart. That chart puts the potential extract of wheat around 1.039, by the way.
I think beertracker is saying that his yield at 74% efficiency is 32 point-gal/lb, which would make the actual potential 1.043. I think that’s a little high.
My yield is .3 potential extract or 1.036 specific gravity when using raw “unmalted” spelt on my system at 74% efficiency. Sorry for any confusion! :-[