Hi - I've started using some new equipment, and had some unexpected numbers on my last brew, so I'm trying to dig into the math a bit.

Total Mash Water: 10.13 gal @ 157 F

Grain: 12.24 lb

Grain Absorption: set @ 0.85 fl oz/oz ==> 1.30 gal

BeerSmith tells me that the water available from the mash should be 8.82 gallons - which makes sense I think @ mash temperature (10.13 gal - 1.30 gal = 8.83 gal).

If I take the 8.82 post mash number and adjust it for temperature, I calculate 8.82 gal * (8.17 lb/gal @ 155 / 8.00 lb/gal @ 212) = 9.01 gal preboil.

But then my estimated pre-boil volume is also 8.82 gal. I would have thought that this would have been at boiling temperatures, as the math for boiloff and cooling shrinkage seems to work out exactly.

Ultimately I'm trying to back-calculate a measured grain absorption so that I can adjust, but the temperatures for the volumes have me scratching my head as well.

Can anyone point me in the right direction here?

- Is the "Water Available from Mash" field @ mash temperature?
- Is the "Estimated Pre-Boil Volume" field @ boiling temperature?
- What measurements (at what temperatures) do I need to calculate actual grain absorption?

I've looked through the documentation and forum and had trouble finding an answer. Thanks.