It calculates based on volume of the combined ingredients. I assume dissolving 1 pint of honey in 9 pints of water will result in less than 10 pints of total volume. I don't know exactly how much, but guessing 9.5 pints total, and using raw honey and raisins as the fermentables, I get 11% ABV with the high attenuation D47 yeast, and 8.7% with the low attenuation S-04.
Caramelization will reduce the fermentability of the honey, but I am not sure by how much. My guess is that it's a small effect.
(All this is wrong, go to edit) I would expect this mead to be high ABV, in the 12-13% range.
The rule of thumb I've heard, and has been good in my experience is 1.035 SG per 1 lb honey per 1 gallon of water. The 3 lbs in 1 gallons would come out to a ~1.105 SG, which is a bit over 13%.
Though, the sugar content of honey varies from batch to batch, and the non ferment-able sugars from the caramelization process, I would expect anywhere from 9-12%. The more caramelization, the more "burnt sugars", the less ABV.~
EDIT: I grossly miscalculated the weight oz to lbs. This is only 1.5 lbs, which would be ~5-6%, making it more akin the ABV of a beer. Same caveat that it would have probably been lower due to the unfermentable sugars.
Most mead I’ve had is similar percentage-wise to wine, yeah. I’m sure it’s possible to fluctuate it up and down, much like sake, depending on the recipe.
Which yeast you use could be very important too!: Different yeasts "pack up shop" during fermentation at different levels of ethanol. It's their own waste-product, that humans love, that stops them, but some types of yeast can put up with much higher levels than others! (though there are other factors too like Ph/pressure/mineralisation/etc).
Some yeast strains keep fermenting to (tolerate) a much higher ethanol percent than others, and the result of these more 'vigorous' yeasts is generally a 'dryer' result in brewing terms: A less 'sweet' result because all the sugars have been 'dried' out (ie roughly, consumed and converted to ethanol). This is not the only axis to think about here though! For mead to be 'sweet' in the end it either has to use a yeast that gives-up (for that much sugar) and hope that nothing else can live in there (not a bad bet for partially-fermented-honey actually), or to be sweetened after-the-fact (probably more common in modern 'Mead' products).
Fermentation involving a community of microorganisms (not just yeast) can often end up far dryer (especially given the time-frames they talk about in the article)! Many bugs can consume the 'waste' products that each other makes, and this variety can create enzymatically-linked cascades of molecular conversion-in-phases that can result in all sorts of unexpected "processing" of the "raw" molecules in the brew, including the hops components (if beer) and I'd think all those spices in traditional mead-recipes were probably undergoing some transformations too! Fascinating!
https://www.brewersfriend.com/homebrew/recipe/calculator
It calculates based on volume of the combined ingredients. I assume dissolving 1 pint of honey in 9 pints of water will result in less than 10 pints of total volume. I don't know exactly how much, but guessing 9.5 pints total, and using raw honey and raisins as the fermentables, I get 11% ABV with the high attenuation D47 yeast, and 8.7% with the low attenuation S-04.
Caramelization will reduce the fermentability of the honey, but I am not sure by how much. My guess is that it's a small effect.