Just about every batch I’ve bottled so far as been undercarbed. I’ve tried both sucrose and dextrose to about the same success. I was using our hosts calculator and priming to about 2.1-2.2 vols. I decided on my IPA I just bottled to try to correct the problem. I ended up using www.brewersfriend.com calculator which appears to give slightly higher values and i decided to bump it up a bit to 2.4 vols. I believe I ended up priming with 4.3oz of dextrose for 5 gallons (47 bottles to be exact). Does that sound like an excessive amount of priming sugar? It’s quite a bit more than I usually use (was using 3.5oz before) but my flat beers are getting a bit frustrating.
Sounds right. You’re fine.
2.1 - 2.2 volumes is pretty low for any style of beer. Unless you are trying to make them “cask like.” to put it in perspective Bud Light 2.7 volumes and most wheat beers are three plus volumes
I think 2vol is adequate. Maybe the temp you’re inputing to the calculator, is lower than the ber actually gets? Ferm temp puts it several degrees warmer than ambient, and that would be the temp at which the CO2 dissolves. Results in an over-estimate of residual CO2 and under-estimate of needed sugar.
They generally send 5oz of priming sugar for a kit so you’re in the ballpark. Unless you fermented pretty cool, this won’t be over-carbonated by any means. YOu might look at the mrmalty.com calculator, it shows volumes for all the styles. I have used it successfully, although honestly carbonation is kind of a hit-or-miss thing for me. Over-carbonation being more frequent for me than under-carbonation. YOu can recover from over-carb with a pitcher, under-carb is the one you want to avoid as you’ve found.