couple of beer math questions for my spreadsheet

[twd000]

when people list grains as a percentage, rather than weight, are they basing that on weight, or potential gravity points per gallon?

won't make a huge difference for some recipes, but if I come across a recipe with 95% 2-row @ 1.036 PPG, and 5% roasted barley @ 1.025 PPG, I need to know whether that roasted barley should be 5% of the total grain weight, or 5% of the total original gravity

and secondly, when people list mash efficiency, which volume is used? Total strike water volume? Or volume into the kettle after runoff/sparge?

 

[VikeMan]

when people list grains as a percentage, rather than weight, are they basing that on weight, or potential gravity points per gallon?

Always (or almost always) weight.

and secondly, when people list mash efficiency, which volume is used? Total strike water volume? Or volume into the kettle after runoff/sparge?

Mash efficiency is the percentage of total potential sugars and dextrins that actually make it into the kettle. When computing it, you need to use the volume that made it into the kettle (either pre-boil or post-boil) and the corresponding gravity.

There are other also other types of efficiency that can be measured and/or inferred.

 

[Kickass]

This description and calculator is very helpful.

https://www.brewersfriend.com/brewhouse-efficiency/