Now you can easily calculate enchants on your Minecraft items with this Minecraft Enchantment Calculator. Calculate the possible enchantments on a given item/book at a given level, or calculate the chance of getting an enchantment on a certain item at any given level (Reverse Calc). And, using the XP Calculator, you can find out how many of a given mob/block to kill/mine/smelt to get to the level you want. Updated with the algorithm used as of Minecraft 1.6.4, as described on the Minecraft Wiki.