Minecraft Enchantment Calculator
This calculator covers three fixed pieces of Minecraft Java Edition enchanting arithmetic. Give it a bookshelf count and it returns the range, average and exact probability of each of the three level requirements the enchanting table can offer, which is how fifteen bookshelves turns out to be the number that guarantees a level 30. Give it an enchantment cost and the prior work counts of two items and it returns the anvil bill, including the doubling penalty and whether the combine crosses the 40 level survival limit. A third mode converts between levels and experience points. The per-enchantment anvil multipliers are not built in, so the anvil mode asks for that part of the cost rather than guessing at it.