Just racked my first 5 gallon batch from my primary to secondary fermenter. After finishing, I realized that my 5 gallon batch is now a little over 4.5 gallons in my secondary fermenter. I’m sure I left a small amount of beer in the primary with the trub, but it certainly wasn’t half a gallon.
Yea, I am not sure about losing .5 gallon though, unless you had a ton of trub. Not sure what you used to guage your initial 5 gallons, but bucket markings may not be reliable.
I did indeed use the bucket markings, but I just compared the two buckets I used and they may not be accurate, but the markings are consistent with one another. Which tells me that I did indeed lose ~.5 Gal somewhere.
A good example of losing a lot of volume, if you don’t plan properly (and then, even if you do), is with NB’s Surly Furious kit. The 8+ oz of dry hops just absorbs a ton of the beer; I bet I lose half a gallon or more from that alone, every time.
As 560sdl mentioned, shoot for 5.25 to 5.5 gallons in the primary, so that your final bottling/kegging volume is 4.75 to 5.0 gallons. As this answer may suggest, yes, loss in volume from transferring steps is normal and expected.