Starter volume

Hey all, I did a quick search for this question and couldn't find an answer right off. Should one factor in the volume of a starter when topping off for a partial boil? Yesterday I did a 5 gallon batch where I boiled 5 gallons and ended up with about 4 gallons of wort. I topped off with chilled water to get to 5 gallons, aerated and then pitched a 1.5 liter starter. According to my markings on the carboy, I was close to 5.5 gallons after pitching.

Should I have only topped off to about 4.5 gallons of wort to leave room for my starter? Or should I just adjust my recipe calculations to reflect that I actually did a 5.5 gallon batch?

Depends on the difference between the starter OG and your batch OG. If they were the same, just treat it as 5.5 gallons. If they were different, use a dilution calculator to calculate the OG.

In the future, consider chilling the starter and decanting the starter beer. Many, including myself, do this to avoid any potential flavor impact of the starter. Many starters worts have a different composition than the rest of the batch and may have been fermented at higher temperatures with the potential off-flavors that result.

They were definitely different, my starter og was 1.036 and my batch og was supposed to be 1.059. I say supposed to be because I dropped and shattered my hydrometer as I was walking it over to the sanitation bucket. Not even sure why I was sanitizing it given the fact that I was not going to put the sample back into the carboy. Oh well. If I kick the batch to 5.5 gallons in the calculator my og should have been closer to 1.054, but you're saying that it's likely somewhere between there based on dilution? I guess that would be right because the calculator assumes the extra half gallon is water and not a starter.

The recipe was for a partial mash pale ale, but for the starter I used 150g of extra light DME. I figured that any flavors produced in the starter would be negligible, as I did it about 24 hours before pitching.

So in the future, should I just use the same DME that will make up the majority of my fermentables?

It's somewhere between the two worts, but it's weighted toward the larger volume (heavily weighted toward your batch SG), so the impact is relatively small. Since you didn't measure the batch SG, you're guessing anyway and the impact isn't going to matter. If the 5 gallons was 1.059, adding 0.5 gal of 1.036 wort would yield 5.5 gallons at 1.057.

You're right that the flavor contribution of the starter is negligible, but as I said, many of us ferment starters at a higher temperature. This can have an noticeable impact on beers with clean profiles, particularly lagers. Lager yeast can produce some very unpleasant volatiles at higher temperatures, increasing the risk of impacting the batch. For this reason, we chill the starter to flocculate the yeast and decant the bulk of the fermented starter wort.

If you're planning to pitch the whole starter, try and keep the wort composition and fermentation temperature as similar as practical to the batch wort. I wouldn't go so far as mashing or even steeping, but at least choose extract that will be similar in character to the batch.