I really hate priming calculators, so take my opinion for what it's worth.
most people who are drinking a bottled beer aren't drinking a beer necessarily "to style". What I mean is this- using that calculator means you can have a flat beer (a stout recommended at 1.5 volumes- in other words, flat) or bottle bombs (a weizen at 4+ volumes). Most people who buy commercial bottled beers are accustomed to a co2 volume of 2.2-2.6 volumes. While it's true that if you're drinking a real ale in a pub it might be a cask beer with a beer engine (and pretty flat, and cellar temperature), it's not usually a bottled beer that is 'to style'. I think the whole carbing to style idea is overdone.
For lower carbed beers, I like .75 oz of corn sugar (by weight) per finished gallon of beer. That would be a stout, for example. For others, especially lagers, I use 1 oz of corn sugar per finished gallon of beer. That works perfectly, and I never have overcarbed or undercarbed beer. Those calculators are wonky.