I'm bottling my friends beer tonight. He definitely ended up with less than the 5 gallons he was going for. My question is do I need to adjust the amount of priming sugar? How do I know how much to decrease it by?
Good calculator. I will add it to my toolbox
NickN, most calculators list priming sugar by weight. I do not have a small scale and measure by volume. Granulated sugar is close to 1 oz dry = 1 oz fluid, or .845 gm/cm3
Yes, that's what I do. (I HATE those priming calculators because they try to guestimate residual co2 as well as prime to "style" so many people get overcarbed or undercarbed beer!)
I use .75 ounces of corn sugar (dextrose) per gallon of beer for lower carbed styles, and 1 ounce of corn sugar per gallon of beer for more highly carbed styles. It works perfectly for me, and I never have had undercarbed or overcarbed beer, in all these years.
Unless you really want to make sure you are accurate to style, just go with what you were originally intending. The bottles can take the small difference. Don't make this difficult.