Anvil mechanics



This page explains the mechanics of the anvil. The anvil is primarily used to repair tools, armor, and weapons, which it can do without stripping their enchantments. It can also be used to combine the enchantments of two items, to give an item a custom name, or to crush enemies or other players that walk beneath it while it is falling. All its functions, except for damaging mobs and players, cost experience levels, and some have material costs.

The anvil has five basic functions: Renaming items can be done in the same work step as repairing or combining, provided the experience cost is not too high. In survival mode, the anvil can apply only 39 levels worth of work in a single operation. If the job would cost 40 or more levels, it is rejected as "Too Expensive!" This does not apply in creative mode.
 * Renaming any item, including normal blocks. Note that most blocks lose the rename when placed.
 * Repairing a "tiered" item with units of its material. For example, iron ingots can be used to repair iron tools and armor. Acceptable items for repair have the material to use in their default name, except for chainmail (repaired with iron ingots), turtle shells (repaired with scutes), and elytra (repaired with phantom membranes).
 * Combining two items of the same kind and material that have durability, e.g. iron pickaxes, bows, shears, etc. The durabilities combine similar to using a crafting table, and the enchantments are combined following rules detailed below.
 * Combining a tool with an enchanted book to add the book's enchantment to the tool. This costs much less than combining enchantments from two similar items, and can give enchantments to items that they could not get at an enchanting table.
 * Crushing any players or mobs who happen to walk under or be under the anvil while it is falling.

Anvil Uses
Anvil uses are the number of times an item has been used in an anvil.

Every time an item has been used in an anvil, it gets one anvil use. If the player adds an enchanted book that had never been used in an anvil with a sword that had never been used in an anvil, then the sword gains one anvil use.

As an item gets more anvil uses, the experience required to use the item in the anvil increases to the point where it says "Too expensive!"

Adding two items with the same number of anvil uses adds one anvil use to the final item. For example, two items with two anvil uses are combined into one item with three anvil uses.

Adding two items having different anvil uses results in an item with one more than the highest uses of the two original items. For example, an item with three anvil use and an item with two anvil uses combine into one item with four anvil uses.

Using an enchantment table on a item does not affect anvil uses.

The formula for prior use penalty is:

(prior use penalty) = 2^(Anvil use count) - 1

Item repair on a crafting grid removes all prior work penalties, and also removes any enchantments. If a grindstone is used, the item keeps its custom name but loses its enchantments and prior work penalties, and some XP from enchantments can be reclaimed.

Renaming
Renaming always costs a single level, in addition to any prior work penalty. Renaming does not increase the prior work penalty.

If the item is being renamed only, without being repaired or enchanted, the maximum level cost is 39 levels even if the prior work penalty is higher. However, once the penalty reaches or exceeds 2147483647, further renames become impossible.

Stackable items can be renamed as a stack while paying a single prior work penalty and a single level for the rename. Note that renamed items, in general, do not stack with normal items, and renamed blocks which do not normally store block entity data lose their name when placed. Blocks such as chests and shulker boxes which do have associated block entity data retain their custom names.

The custom name of a renamed item can be reset by renaming it to a name that consists of spaces. However, that item's repair cost is not reset. Therefore, it cannot be stacked with other items of the same type with different repair costs.

Unit repair
Some items are "tiered" and can be repaired using units of its repair material, each unit restores up to 25% total durability of the item (rounded down) and costs 1 level per unit of material used in addition to any applicable prior work penalties.
 * The material to use is specific for each item (see the table below). For many items, this is determined by its tier or armor material.
 * If the stack of raw material has been renamed, its prior work penalty is paid once regardless of the number of units being used in the repair.
 * Due to the rapid increase in prior work penalty for each repair, it is generally most effective to use an item almost to the breaking point and then repair using four units of raw material at once (or by combining with a newly crafted instance of the item).

Repairable items

Combining items
The anvil can be used to combine two items of the same type and material, or an item with an enchanted book. This applies only to items with durability: weapons, shields, tools, and armor, as well as enchanted books. The first/left item is the target item, the second/right item is the sacrifice item, which is destroyed. Combining two similar items does either or both of two things. Each of these costs levels, but if they're both done at once, part of the cost is shared:
 * The target is repaired, adding the durability of the sacrifice plus a bonus of 12% of the maximum durability, up to the item's maximum durability. If the target item is undamaged, there is no charge for repair, otherwise, the cost is 2 levels.
 * If the sacrifice has enchantments, it also tries to combine the sacrifice's enchantments onto the target. Regardless of whether any enchantments on the target are actually changed, the cost is based on the total enchantments on the target and sacrifice. For each enchantment on the sacrifice:
 * If the target has the enchantment as well...
 * and the sacrifice level is greater, the target is raised to the sacrifice's level.
 * and the sacrifice level is equal, the target gains one level, unless it is already at the maximum level for that enchantment.
 * and the sacrifice level is less, nothing changes on the target.
 * If the target does not have the enchantment, it gains all levels of that enchantment, unless it already has an incompatible enchantment. Enchantments are incompatible if both are in one of the following groups:
 * Sword: Sharpness, Smite, and Bane of Arthropods
 * Tool: Fortune and Silk Touch (as of Java version 1.12.2 you can combine these; the sacrifice item's enchantment is lost)
 * Armor: Protection, Fire Protection, Blast Protection, Projectile Protection
 * Boots: Depth Strider and Frost Walker
 * Bow: Infinity and Mending
 * Crossbow: Multishot and Piercing
 * Trident: Loyalty and Riptide or Channeling and Riptide
 * Books: Silk Touch and Looting or Silk Touch and Luck of the Sea (and all of the above).

The total cost for combining two similar items is the sum of:
 * Prior Work penalties of both target and sacrifice.
 * If renaming, the extra cost of renaming
 * If the target item is not at full durability, the repair cost of 2 levels.
 * If the sacrifice has enchantments, the enchantment cost.

If the sacrifice is a book, there is no repair, but the anvil tries to combine the book's enchantments onto the target. The item can also be renamed at the same time. The enchantment cost is generally less than for combining two similar items.

Costs for combining enchantments
(This is just the enchanting cost. The total cost outline is in Combining items.)
 * For each enchantment on the sacrifice:
 * Ignore any enchantment that cannot be applied to the target (e.g. Protection on a sword).
 * Add one level for every incompatible enchantment on the target (In Java Edition).
 * If the enchantment is compatible with the existing enchantments on the target:
 * For Java Edition, add the final level of the enchantment on the resulting item multiplied by the multiplier from the table below.
 * For Bedrock Edition, add the difference between the final level and the initial level on the target item multiplied by the multiplier from the table below.

Examples:
 * Dealing with equal enchantments:
 * In the first slot, the target is a sword with Sharpness III, Knockback II, and Looting III.
 * In the second slot, the sacrifice is a sword with Sharpness III and Looting III.
 * For the Sharpness III enchantment on the sacrifice: Since the target has an equal level, add one to the target's Sharpness level giving Sharpness IV. In Java, Add 4 (multiplier 1 times 4 levels) and in Bedrock, add 1 (multiplier 1 times the increase in levels 1) to the level cost for Sharpness IV.
 * For the Looting III enchantment on the sacrifice: Since the maximum level for Looting is III, the target remains at Looting III. In Java 12 (multiplier 4 times 3 levels) is still added to the level cost while in Bedrock, 0 is added since the level did not change.
 * Thus, the enchanting cost is 16 in Java and 1 in Bedrock. The total cost for the work includes any prior work penalties, repair costs, and rename costs.
 * If combined in the other order (the sword having three enchantments as the sacrifice), there would also be a cost of 4 (level 2 times multiplier 2) for the Knockback II enchantment for both Java and Bedrock (since the target has zero levels in Knockback), giving a total enchantment cost of 20 levels in Java and 5 levels in Bedrock.
 * Dealing with unequal enchantments:
 * In the first slot, the target is a sword with Sharpness III, Knockback II, and Looting I.
 * In the second slot, the sacrifice is a sword with Sharpness I and Looting III.
 * For the Sharpness I enchantment on the sacrifice: Since the target has a higher level, the target keeps Sharpness III. But in Java, 3 (multiplier 1 times 3 levels) is still added to the level cost. In Bedrock, since the level on the target is unchanged, the cost added is 0.
 * For the Looting III enchantment on the sacrifice: Since the target has a lower level, it is upgraded to Looting III. In Java, add 12 (multiplier 4 times 3 levels) to the level cost. In Bedrock, add 8 (multiplier 4 times the increase in levels 2)
 * Thus, the enchanting cost is 15 in Java and 8 in Bedrock. The total cost for the work includes any prior work penalties, repair costs, and rename costs.
 * If combined in the other order (the sword having three enchantments as the sacrifice), there would also be a cost of 4 (multiplier 2 times 2 levels) for adding the Knockback II enchantment, giving a total enchantment cost of 19 levels in Java. In Bedrock, the looting level would be unchanged, the sharpness cost would be 2 (multiplier 1 times the increase in levels 2) plus the Knockback cost gives a total enchantment cost of 6 levels.
 * Dealing with conflicting enchantments:
 * In the first slot, the target is a sword with Sharpness II and Looting II.
 * In the second slot, the sacrifice is a sword with Smite V and Looting II.
 * For the Smite V enchantment on the sacrifice: Since Smite is incompatible with Sharpness, add 1 level in Java, nothing for Bedrock. The target keeps Sharpness II.
 * For the Looting II enchantment on the sacrifice: Since the target has an equal level, add one to the target's Looting level giving Looting III. In Java, add 12 (multiplier 4 times 3 levels) to the level cost for Looting III. In Bedrock, add 4 (multiplier 4 times the increase in levels 1) to the level cost for Looting.
 * Thus, the enchanting cost is 13 in Java and 4 for Bedrock. The total cost for the work includes any prior work penalties, repair costs, and rename costs.
 * If combined in the other order (the Sharpness sword as the sacrifice), the cost would again be 13 in Java and 4 in Bedrock with the result having Smite V and Looting III.
 * Using books:
 * In the first slot, the target is a sword with Looting II.
 * In the second slot, the sacrifice is a book with Protection III, Sharpness I, and Looting II.
 * For the Protection III enchantment on the sacrifice: Since Protection is incompatible with swords, ignore it.
 * For the Sharpness I enchantment on the sacrifice: Since the target has no Sharpness, it gets Sharpness I. Add 1 level (multiplier 1 times 1 level) for Sharpness I.
 * For the Looting II enchantment on the sacrifice: Since the target has an equal level, add one to the target's Looting level giving Looting III. In Java, add 6 (multiplier 2 times 3 levels) to the level cost for Looting III. In Bedrock, add 2 (multiplier 2 times the increase in levels 1) to the level cost for Looting.
 * Thus, the enchanting cost is 7 in Java and 3 in Bedrock. The total cost for the work includes any prior work penalties and rename costs.

Planning the enchanting order
There are two important things to notice about the anvil mechanics when planning the order of multiple enchantments to the same item:
 * When combining two items with prior work penalties, while the penalties for both items apply to the cost, only the higher of the penalties of the two items is considered when determining the penalty of the resulting item. For example, when combining two items with 2 workings each, the resulting item has only 3 workings with the fourth consumed by the penalty.
 * The choice of which item to use as the sacrifice matters. For example having a Soul Speed III book in the first slot and a Mending book in the second slot has a cost of 2 levels, but reversing the order of the books results in a cost of 12, even though the resulting book is the same in the two cases.

To minimize the prior work penalties, always combine two items with equal penalties as possible. It is possible to have 7 different enchantments on a single pair of boots. Starting with an unenchanted pair of boots and the 7 enchantments on individual books, the limit on the cost permitted by the anvil is exceeded if trying to combine the books one at a time with the boots. However, it is possible to avoid this by properly pairing up the items. First combine the boots with one of the books, plus the remaining 6 books in 3 pairs. Then combine the boots with one of the books and the other two books that have 2 enchantments each. Finally combine the boots with the book that has 4 enchantments. This results in a pair of boots with 3 workings on it, although in practice 7 workings have taken place.



It is also possible to minimize the cost of combining by carefully pairing up the items for combination. The enchantment with the highest cost should be in the sacrifice slot the least amount of times. For example. To combine the 7 enchantments using the pairing method, one should use the following order:
 * Soul Speed III (12), Thorns III (12), Feather Falling IV (4), Depth Strider III (6), Protection IV (4), Unbreaking III (3), Mending (2)
 * Combining the items pairwise (with the boots in the first slot) the cost is 12+4+4+2=22.
 * The resulting items are: Boots (Soul Speed III), Thorns III+Feather Falling IV (16), Depth Strider III+Protection IV (10), Unbreaking III+Mending (5).
 * The cost of the second round of combination is 16+5=21, plus 4 for the penalties, totalling 25.
 * The resulting items are: Boots (Soul Speed III+Thorns III+Feather Falling IV), Depth Strider III+Protection IV+Unbreaking III+Mending (15).
 * The cost of the last step is 15 plus the two penalties of 3 each, totalling 21.
 * The overall cost is 22+25+21=68 levels.

Enchantment equation
The equation to calculate an enchantment is as follows:

Experience cost = [Value of sacrificed (right placed) item] + [Work Penalty of target (left placed) item] + [Work Penalty of sacrificed (right placed) item] + [Renaming Cost] + [Refilling Durability] + [Incompatible Enchantments (Java Edition)]

The equation to calculate the new value of an item to be enchanted:

New value = [Value of target (left placed) item] + [Value of sacrificed (right placed) item].

Using the 7 enchantment pairing method shown, and looking at just the first enchantment (Diamond Boots + Soul Speed III) as an example:
 * Experience Cost = [Value of Sacrificed item - Soul Speed III (12)] + [Work Penalty of Diamond Boots (0)] + [Work Penalty of Soul Speed III (0)] = 12 Levels.
 * New Value of resulting item = [Value of Diamond Boots (0)] + [Value of Soul Speed III (12)] = 12 Value.

Going to the next level of enchanting with Diamond Boots (Soul Speed III) and Thorns III + Feather Falling IV book:
 * Experience Cost = [Value of Sacrificed item - Thorns III + Feather Falling IV (16)] + [Work Penalty of Diamond Boots (Soul Speed III) (1)] + [Work Penalty of Thorns III + Feather Falling IV book (1)] = 18 Levels.
 * New Value of resulting item = [Value of Diamond Boots (Soul Speed III) (12)] + [Value of Thorns III + Feather Falling IV book (16)] = 28 Value.
 * Remember that the Work Penalty for each item here is a value of 1 because each has been used only once on the anvil previously.

Trivia

 * Enchantments that are added to raw materials (e.g. an iron ingot with Sharpness III) are ignored when doing unit repair, not combined.
 * Because prior work penalty is charged for any rename, it is most economical to rename a weapon before repairing or enchanting it, minimizing the penalty the player must pay for the rename.