How Enchantments Are Chosen

When you click the button for a level 17 enchantment, how does Minecraft decide to apply Sharpness II? Here's an explanation. But first, some terminology:

"Enchantment level" is the cost of the enchantment in experience levels (the green number on the button).

"Enchantment power" is the strength of the particular enchantment. For example, "Sharpness IV" has power 4.

The enchantment algorithm uses a three-step process.

Step One

Apply modifiers to the enchantment level

The first thing that Minecraft does is apply two modifiers to the base enchantment level (the green number, and the number of experience levels you actually pay). Each modifier is restricted to a certain range, with numbers close to the middle of the range more common than those near the ends.

The first modifier is based on the item's "enchantability," which depends on the material and the type of the item (see the table below). Minecraft picks a number between 0 and half of the enchantability (with enchantability / 4 the most probable result), then adds that number plus one to the enchantment level.

Armor Sword

or Tool Wood 15 Leather 15 Stone 5 Iron 9 14 Chain 12 Diamond 10 10 Gold 25 22

Bows and books have enchantability 1.

Next, Minecraft picks a value between 0.85 and 1.15, with values closer to 1.0 being more likely. The enchantment level is multiplied by this value (so it increases or decreases by up to 15%) and then rounded to the nearest integer.

Step Two

Find possible enchantments

Now, based on the modified level, Minecraft makes a list of all enchantment types that can be applied to the target item along with the power that each enchantment will have.

The power of each enchantment type is determined by the level and the values in the table below. For each power value of an enchantment type, there is a minimum and maximum level that can produce the enchantment at that power. If the modified enchantment level is within the range, then the enchantment will be assigned that power. If the level is within two overlapping ranges for the same enchantment type, the higher power value is used.

I II III IV V Protection 1 21 12 32 23 43 34 54 -- Fire Protection 10 22 18 30 26 38 34 46 -- Feather Fall 5 15 11 21 17 27 23 33 -- Blast Protection 5 17 13 25 21 33 29 41 -- Projectile Protection 3 18 9 24 15 30 21 36 -- Respiration 10 40 20 50 30 60 -- -- Aqua Affinity 1 41 -- -- -- -- Thorns 10 60 30 80 50 100 -- -- Sharpness 1 21 12 32 23 43 34 54 45 65 Smite 5 25 13 33 21 41 29 49 37 57 Bane of Arthropods 5 25 13 33 21 41 29 49 37 57 Knockback 5 55 25 75 -- -- -- Fire Aspect 10 60 30 80 -- -- -- Looting 15 65 24 74 33 83 -- -- Efficiency 1 51 11 61 21 71 31 81 41 91 Silk Touch 15 65 -- -- -- -- Unbreaking 5 55 13 63 21 71 -- -- Fortune 15 65 24 74 33 83 -- -- Power 1 16 11 26 21 36 31 46 41 56 Punch 12 37 32 57 -- -- -- Flame 20 50 -- -- -- -- Infinity 20 50 -- -- -- --

An example: Suppose we are enchanting a sword with a modified enchantment level of 21. If the sword gets the Sharpness enchantment, it will get Sharpness II because 21 is in the power-II range for Sharpness (12-32). 21 is also in the power-I range (1-21), but the higher power value will win over the lower. If the sword gets Smite, then it will be Smite III, because 21 is in the power-III range for Smite (21-41).

Note that extremely high modified enchantment levels can fall outside the ranges of all valid enchantments for the item. If this happens, the item is left unenchanted, but you are not charged any experience levels and can try enchanting it again.

Step Three

Select a set of enchantments from the list

Now that it's got a list of the possible enchantments for the item, Minecraft has to pick some of them that will actually be applied.

You always get at least one enchantment. The first enchantment is picked from the list based on the weights below.

Weight Protection 10 Fire Protection 5 Feather Fall 5 Blast Protection 2 Projectile Protection 5 Respiration 2 Aqua Affinity 2 Thorns 1 Sharpness 10 Smite 5 Bane of Arthropods 5 Knockback 5 Fire Aspect 2 Looting 2 Efficiency 10 Silk Touch 1 Unbreaking 5 Fortune 2 Power 10 Punch 2 Flame 2 Infinity 1

For example, suppose the item is a piece of armor with both Protection and Respiration available. Protection has 10 chances to be selected compared to 2 for Respiration, so the probability of getting Protection is about 5 times higher than the probability of Respiration.

After the first element is selected, there is a chance of receiving more, based on this algorithm:

With probability (modified level + 1) / 50 , keep going. Otherwise, stop picking bonus enchantments. Remove from the list of possible enchantments anything that conflicts with previously-chosen enchantments. For example, if Smite was already picked, Sharpness and Bane of Arthropods will be removed at this step. See below for more info on conflicts. Pick one enchantment from the remaining possible enchantments (based on the weights, as before) and apply it to the item. Divide the modified level in half (rounded down) and repeat from step 1.

When enchanting a book, if this process selects more than one enchantment, the game chooses one enchantment at random to keep and discards the rest.

Here are the rules for enchantment conflicts: