calculating SG of first runnings

Is there a formula that can be used to calculate (or some way to estimate) the gravity of first runnings?

I ask because I want to attempt no sparge brewing, but I am constrained to a partial boil, which means I am limited in the amount of runoff I can collect, which affects how much I can mash. I'm pretty sure I can figure everything out that I need in terms of grain and water if I only had a way to estimate/calculate the gravity of first runnings.

There's actually a chart somewhere on http://braukaiser.com

Actually... he has a spreadsheet now that does the work.

http://braukaiser.com/download/batch_sparge_simulator.xls

Thanks. I should have figured Kai had something like this. In fact, he's got exactly the chart I was looking for

JLem said:

Thanks. I should have figured Kai had something like this. In fact, he's got exactly the chart I was looking for

Click to expand...

Yup.... that's the chart. I was looking for that when I stumbled across the spreadsheet.