Okay, given my lack of ninja searching skills, this has probably been asked and answered before, but....
I have one the party start mini 5L kegging setups, but have not thus far been very impressed. Given, however, that the setup is the closest I will get to kegging in the next few years, I had a question about how to do the priming sugar in a split batch. I know that the basic procedure is to prime a 5 gallon batch with 3oz of dextrose, or about 0.6 oz of dextrose per gallon. Now, I want to fill one keg per the next few batches to see if I can get a good seal, rather than risk the entire batch.
My question becomes, how best to figure the dextrose to bottle the rest of the batch. Assuming that I have 5 gallons to start, I lose approximately 1.25 gallons to the first keg, I end up needing to bottle 3.75 gallons of beer. If the priming calculator calls for about 5 oz of sugar (to make the math simple - yes, it is a bit high), I assume I would need to find the appropriate fraction of that sugar to make up the balance of the priming liquid.
Therefore, would the correct amount of sugar for bottling be an additional 1.5 oz of dextrose? The math would be the difference of the dextrose, divided by the initial volume and multiplied by the final volume: ((5oz called for - 3oz for the keg priming) / 5 gallon initial volume) * 3.75 remaining volume = 1.5oz necessary to reach desired volume.