First time I've brewed anything and I thought i'd start as simple as possible, so I just got some granulated sugar and apple juice from concentrate. 2L of apple juice, Champagne yeast, and 2 cups of sugar (I couldn't find any recipes anywhere). I measured my starting density to be 1.21 (water being 1.00), and after 2 weeks fermenting at about 22C in a PET demijohn I have a density of 1.06.
I calculate this to give me an ABV of 19% roughly.
This seems to be too high to be accurate, so I wonder if anyone has any suggestions above and beyond just 'your hydrometer isn't working' as to what's happened? Does this sort of measurement sometimes indicate the cider is unsafe to drink or anything like that?
EDIT: All measurements were done at room temperature of 20-25C