I've been told this formula...
25 x liters of mead wanted x ABV % points = grams of honey need
example... for 10 liters of 10% mead...
25 x 10 x 10 = 2 500g
That means 5.5 lbs of honey for a 2.64 gallons batch.
But if I do the calculations in beersmith, or with other calculators... I have really different results.
Here's my recipe.
4Kg Buckwheat honey (80% sugar content) (8.8lbs)
Fruits that will give a total of 1Kg of ferment. sugars (2.2lbs)
That is for a 17L batch, so a 4.5 gallons
lalvin k1-v1116 yeast
If i use the formula with the honey, and calculate the contribution of fruits... It results with 13.0% ABV
With beersmith (with honey yield at 80%), i got 15.5% ABV, but a FG of 0.979!