The anvil’s experience cost looks random until you know the formula. It is actually deterministic: three components add up to the level cost of every single combine. Once you can compute it by hand, the “Too Expensive!” message stops being a mystery. The enchantment calculator does this math for every possible order and returns the cheapest.

The three cost components

Prior-work penalty (kept item) — a surcharge based on how many times the left item has been on an anvil.
Prior-work penalty (sacrificed item) — the same surcharge for the right item.
Enchantment transfer — each enchantment on the sacrificed item, priced as level × rarity multiplier.

Renaming an item adds a flat 1 level; repairing with raw material costs 1 level per unit consumed; and repairing by sacrificing a second copy of the item costs a flat 2 levels. All three are separate from enchantment combining and stack on top of the prior-work penalties.

The prior-work penalty doubles every time

This is the single most important number to understand. The penalty follows 2ⁿ − 1 where n is the number of previous anvil uses:

0 prior uses → 0-level penalty
1 prior use → 1-level penalty
2 prior uses → 3-level penalty
3 prior uses → 7-level penalty
4 prior uses → 15-level penalty
5 prior uses → 31-level penalty
6 prior uses → 63-level penalty

Because this penalty is charged for both items in every future combine, an item that has passed through the anvil six times already carries a 63-level surcharge — well past the survival cap — before any enchantment is even transferred. That is the entire reason combine order matters.

The rarity multipliers

From a book, enchantments cost their level times 1, 2, or 4 depending on rarity (applying directly from another tool doubles each). The 8 very-rare enchantments at multiplier 4 are the dangerous ones — moving a single very-rare enchantment a second time costs as much as moving four common ones.

Worked example: an Infinity bow

A Bow with Power V, Punch II, Flame, Infinity and Unbreaking III. The cheapest survival-legal order the optimizer finds costs 29 levels, peaking at 11 levels on its priciest step:

Bow + Book: Power V — 5 levels
Book: Punch II + Book: Flame I — 2 levels
Bow (Power V) + Book (Punch II, Flame I) — 8 levels
Book: Infinity I + Book: Unbreaking III — 3 levels
Bow (Power V, Punch II, Flame I) + Book (Infinity I, Unbreaking III) — 11 levels

The 39-level “Too Expensive” cap

In Survival and Adventure mode the anvil refuses any single operation worth 40 levels or more. The cap is per-step, not per-project: you may spend far more than 39 levels across a sequence of combines, but no individual step may reach 40. Creative mode removes the cap. When a plan crosses the line, the calculator marks it red and points at the step that broke it.

Java vs Bedrock

The formula above is shared by both editions. The only practical difference for enchant combining is that Impaling costs half as much in Bedrock, and Bedrock omits the +1 surcharge Java applies per incompatible enchantment. For a normal, non-conflicting loadout the cheapest order is the same in both — read more on the calculator page, where you can toggle editions directly.

Minecraft Anvil Cost Explained