Topping off to 5.5 0r 6 gallons

I only brew extract and just finished a Petit Orange. While my ABV came in right on target at 6.0% I was able to bottle only 4 gallons. I have a 6.5 gallon carbon for my primary and was considering of topping off at 5.5- 6 gallons instead of the usual 5 gallons. My question is will my ABV be affected proportionally? Since my wort will be 10-20% higher, will my ABV be 10-20% lower?

I don’t think your wort would be higher with the extra water it will be lower as will your ABV. I wouldn’t add more than 5.5 gallons to a 6.5 gallon carboy. If you want to maintain the same abv as the recipe add a little more DME. Take your reading when chilling then boil your top off water and DME to compensate. There ste online calculators that will tell you how much you need. That’s how we do it with all grain if our efficiency I’d off.

A broad general rule that works pretty well is : 1 lb. DME or 1 lb sugar or 1lb honey will increase your SG by about 8 points in a 5G batch.
Another ballpark is that 2cups of DME = about 1 lb. Probably the same with sugar, but I always use honey instead of sugar, so haven’t actually weighed sugar in years.
Always check your SG at about the 10 minute point so you can adjust your OG if needed.

Thanks for the information and tips. Will use them when I top to 5.5.

what now if you start with five gallon boil. boil separate the grains in one gal water than add it to the five gal and add extra dme. end of boil you end up with five gal wort i do use this way add extra dme and lme 15 min before end of boil add some more lme .i add the first can of lme begin of the boil. second can lme 15 min before end of boil. do transfer to fermenting bucket. i do have 5 to 5.5 gal wort and my abv perfect

I usually can figure 10 points of gain with 1 lb of table sugar… FYI… Sneezles61

Every extract kit that I have brewed mentions to top off the primary fermentor to the 5 gallon mark shortly before you add the yeast. It gets you the correct amount of beer and also helps cool it down to pitching temp. Is there a chance that you just forgot to top it off when you were supposed to?

Its step 9 on the directions sheet.

I am about to share my La Petite Orange with the family in about 20 minutes myself. It turned out wonderful. Reminds me so much of a Weihenstephaner Hefeweissbier even though its not a hefe. Such a good beer either way tho