The trading system is a gameplay mechanic that allows players to trade emeralds for items (and vice-versa) with NPC villagers.
Right-clicking a villager will allow a player to trade with the villager. Villagers will make offers based on their profession, and will only make trades based on what offers they are making.
Different offers may be viewed by pressing the left and right buttons next to the currently displayed offer. All offers involve emerald as a currency, and some item pertinent to the villager's profession. Trading allows the acquisition of uncommon items that would otherwise be fairly difficult to obtain, such as chainmail armor. It is also the only legitimate method of acquiring bottle o' enchanting in Survival mode.
A villager will never offer to buy/sell the same item at different prices or quantities (for example, no villager will offer to buy either 16 raw pork or 17 raw pork: there can only be one offer to buy raw pork).
However, the quantities and prices may vary from villager to villager, and a villager's own quantities/prices may change when they generate new offers.All villagers initially have only one offer to make. They can generate new offers when the last offer available (rightmost on their list of offers) has been traded at least once. Note that the trading GUI must be closed before a villager will generate a new offer.
When they do, they become surrounded with purple particles for a moment. New offers may involve items a villager was already buying/selling: in this case, the newly generated offer will overwrite the previous one, allowing a villager's prices (or priest's enchantments) to change. Although there is no maximum limit on the number of offers an individual villager can make, they can only have one offer for each type of item they can trade.
In addition, when a villager already has many offers, there is a high probability that a newly generated offer will be of an item they already offer: thus the old offer will be overwritten, and there will not be any new offer slot added to the villager.
Villagers will remove offers if the offer has been used some number of times and it is not the villager's only offer. The chance of an offer's removal is random, but an offer must be used at least 3 times before it is eligible for removal. After an offer has been used 13 times, it is guaranteed to be removed if you close the interface after trading it (this is true even if all 13 trades have been done at once).
Prior to the Pretty Scary Update (v1.4), it was possible to trade more than 13 times on a single offer because offers were not removed until the trading interface had closed. This meant you could buy an offer as many times as you could afford with one inventory. Currently, villagers can halt trading on a particular item once the conditions for removal have been met even if the trading window is still open. Once the trading window is closed and reopened, the offer will still be displayed, but red X's will indicate that the offer is no longer available.
However, only one offer can be removed after the trading interface is closed: if you trade multiple offers beyond the limit, only the last one traded will be removed. In this way, an offer with more than 13 uses can be kept, and the game does not check offers for removal until the offer is traded.In addition, if an offer is the last offer available, it is never removed even if its uses exceed 12. Once it is no longer the last offer, of course, it is eligible for removal. When an offer is removed, it has the same particle effect as an offer being created.
The following table lists the minimum and maximum offers that a villager will make when buying and selling items.
Farmer
Librarian
| Buys | ||||
|---|---|---|---|---|
| Item | Quantity | Price | Probability Value | Actual Probability |
| Paper | 24-35 | 1 | 0.8 | 24.8384% |
| Book | 11-12 | 1 | 0.8 | 24.8384% |
| Written Book | 1 | 1 | 0.3 | 7.9476% |
| Gold Ingot | 8-9 | 1 | N/A | 0.2666% |
Priest
| Buys | ||||
|---|---|---|---|---|
| Item | Quantity | Price | Probability Value | Actual Probability |
| Gold Ingot | 8-9 | 1 | N/A | 15.6036% |
| Sells | ||||
|---|---|---|---|---|
| Item | Quantity | Price | Probability Value | Actual Probability |
| Eye of Ender | 1 | 7-10 | 0.3 | 16.1039% |
| Bottle o' Enchanting | 2-4 | 1 | 0.2 | 10.2716% |
| Redstone | 2-4 | 1 | 0.4 | 22.5541% |
| Glowstone | 2-3 | 1 | 0.3 | 16.1039% |
Blacksmith
Butcher
| Buys | ||||
|---|---|---|---|---|
| Item | Quantity | Price | Probability Value | Actual Probability |
| Coal or Charcoal | 16-23 | 1 | 0.7 | 21.0549% |
| Raw Porkchop | 14-17 | 1 | 0.5 | 14.0096% |
| Raw Beef | 14-17 | 1 | 0.5 | 14.0096% |
| Gold Ingot | 8-9 | 1 | N/A | 0.794% |
