What actually IS boil size?

Haven't found this answer. By the time I added 5.5 pounds of DME and steeping grains, I had only used 2.5 gallons of water in my 4 gallon pot. The whole was well over 3.5 gallons (I had about a quarter inch to the top - thank God I don't seem to get boil overs - my theory is that the stove heats slow enough to avoid it).

Question is - did I do a 3.5+ gallon boil or just a 2.5 gallon boil in terms of figuring out effectiveness/hop utilization?

Boil size is the amount of liquid in the pot, so 3.5+ in your present case.

The phrase "boil size" is referring to the amount of liquid boiled in relation to the total wort to be fermented.
It may be a “Full” or “Partial” boil.

If you added water to fill the fermenter AFTER the boil, you did a “Partial” boil.

If on the other hand you are doing a 3.5 gallon batch with no added water, then you did a “FULL” boil.

FYI: While some believe this can effect hop utilization or effectiveness, I read or listened to in a POD cast somewhere that tests were done that showed little or no difference between Full and partial boils.

Redpiper said:

By the time I added 5.5 pounds of DME and steeping grains, I had only used 2.5 gallons of water in my 4 gallon pot. The whole was well over 3.5 gallons

Click to expand...

Hoping you took those steeped grains out before you boiled?