Dialing in my system

Brewed a 3 gallon biab batch this past weekend. After the 60 min boil I ended up with 2.75 gallons in the fermentor, including trub, so about 2.5 gallons of liquid. Post boil gravity was 1.050, looking for 1.044.So I topped up with purified water(about 1/2 gal) to 3.25 gal in the fermentor, figuring I had roughly 3 gal of liquid now.

My question is in trying to estimate OG. Didn’t want to take another sample since it’s a small batch. Here’s my math, please correct me if I’m off:

.5 gal @ 0 SG
2.5 gal @ >050 SG

Total 3.0 gal/.5 = 6
50 x 5 + 1 x 0 = 250/6 = 41.667 so, OG of +/- 1.042

I’m sure even if this is correct, there is an easier formula.

Thanks for any schooling. If nothing else, I’ve learned that I’m boiling off more than my system had allowed for, so adjusting shouldn’t be too hard.

:cheers:

Ron

Haha. Just saw the brewer’s friend dilution calculator posted by Mattnaik in another thread. My calcs were right, though roundabout. The calculator is much easier. Thanks to Matt.

:cheers:

Ron

You did it right. I just take 2.5 gal original x 50 SG original / 3 gal new = 42 SG new, or 1.042. Same math, a bit quicker & easier. The main concept is that volume x SG always stays constant if you’re just playing with water content to adjust volume. In other words the total amount of sugar always stays the same, and that can be calculated roughly by volume x SG.