Help Modifying Sweet Stout

[CarlosHernandez]

Thinking about brewing JZ's Sweet Stout from "Brewing Classic Styles" and i needed some help make it a bit bigger. Recipe cals for 1.060 OG - 1.023 FG (61% attenuation) about 5% ABV. I was thinking something closer to 7% ABV. The OG is a little high for a 5% because of the 1 pound of unfermentable lactose powder. Anyhow, my question is how much more base malt should I add to achieve that higher ABV? And how much more IBU's should I add to balance that? Is there a formula I can use for this and future modifications? Thanks in advance.

[Crackin]

Without using brewing software, you can estimate that 1 lb of grain will give you about 37 gravity points multiplied by your mash efficiency divided by the number of gallons. (base malts can be slightly higher, crystal malts can be slightly lower. 37 is an average.)

For example, 1lb x 37pts x .75 (efficiency) / 5.5 gallons = 5 gravity points.

For a 7% version, you probably want a starting gravity of about 1.077 or about 3.4 extra pounds of grain. Remember that your attenuation percentage will increase somewhat, because you are adding a higher percentage of fermentable wort, rather than lactose, so you overall fermentability will increase.

For bittering, just look at the original bittering to gravity point ratio, and recalculate the bittering to maintain this ratio with your new, higher OG.

If your original IBUs were 25, and the original OG was 1.060 that a .42 BU/GU ration. For 1.077 you would need 32 IBUs to maintain the same ratio.

[CarlosHernandez]

Thanks for making it easy to understand Crackin!

Are these formulas from Ray Daniels' book?

[CarlosHernandez]

One more thing... We talked about increasing base malts, but what about specialty grains? How do I factor those into the equation?