Anvil Calculator

A hidden counter on every item and book that rises by 1 each time it survives an anvil. The penalty it adds to a combine is 2 to the power of that count, minus 1 level: 0, 1, 3, 7, 15, 31, 63. Both the target and the sacrifice add theirs, and the result keeps the higher of the two plus 1. That doubling is why combine order matters so much. Renaming counted as anvil work in older versions. In modern Java it costs 1 level flat and does not raise the counter.

Because the penalty depends on the work count, the cheapest plan is usually a balanced bracket: merge books in pairs, merge the merged books, then apply one big book to the item. Adding 8 books one at a time racks up penalties of 1, 3, 7, 15, 31 and 63, while a balanced tree keeps every piece low. This calculator tries every possible bracket and returns the exact cheapest one, and shows you how much it saves.

In Survival, any single anvil use costing more than 39 levels reads Too Expensive and cannot be done, while Creative ignores the cap. Avoid it with the balanced order this tool suggests, by starting from a fresh item with zero prior work, or by settling for one fewer heavy enchantment. If even the optimal plan has a step over 39, that combination cannot be finished in Survival on that item.

Java edition. Bedrock uses the same prior-work doubling but slightly different enchant multipliers and merging rules, so totals can differ by a few levels. The Java anvil formula has been stable for years, so the plan holds across modern versions.