I was just thinking that if you started with just 5 gallons of wort, by the time you filled the bottles there would be quite a bit less then that because you dont use the bottom 1"? What do you actually end up with? How many 12 oz bottles?
I actually make 5.5 gallon batches. After racking twice and loosing some along the way (trub in fermenters), I end up with 5 gallons in the bottles. I get pretty much every last drop out of the bottling bucket, like BeeGee commented.
1 gallon = 128 oz
5 gallons = 640 oz (appx 53 12oz bottles)