NPC drops

Most enemies drop items and/or coins when they are killed. 
== Chance of obtaining a drop ==
To determine the chance for at least one specific item to drop for a given number of enemies with the same chance of dropping said item, use the equation:
{{math|NPC_drops-math-1|inline=y|{{#uesc:<esc>1-(1-\mathit{drop\ chance})^{\mathit{number\ of\ enemies}}</esc>}}}}
:* Example: What is the chance of obtaining a Rod of Discord after defeating 300 Chaos Elementals? Its drop chance is 0.002 ().
:: {{math|NPC_drops-math-2|inline=y|{{#uesc:<esc>1-(1-0.002)^{300} = 0.45151799156631 \approx 0.452</esc>}}}}, which means the chance is about 45.2%.
To find how many enemies are needed to obtain a certain "goal" chance it has dropped at least once, use:
{{math|NPC_drops-math-3|inline=y{{#uesc:<esc>\left\lceil\frac{\ln{(1-\mathit{goal\ chance})}}{\ln{(1-\mathit{drop\ chance})}}\right\rceil</esc>}}}}
:* Example: How many Chaos Elementals have to be defeated to have a chance of 90% (0.9) of obtaining a Rod of Discord? Its drop chance is 0.002 ().
:: {{math|NPC_drops-math-4|{{#uesc:<esc>\left\lceil\frac{\ln{(1-0.9)}}{\ln{(1-0.002)}}\right\rceil=\lceil1150.1408698021\rceil = 1151</esc>}}|inline=y}}, which means 1151 Chaos Elementals have to be defeated.
Note that all chances are in decimal, i.e. 70% = 0.7 etc.
== Item drops ==
Some items are dropped by all enemies (except enemies spawned by statues, Old One's Army enemies, Lunar Events enemies, and Meteor Heads) under certain conditions. Those can be found below.
Item	Condition 	Amount	Chance
 	During Hardmode in the Underground Hallow. 	1 	/
 	During Hardmode in the Underground Corruption/Crimson. 	1 	/
 	During Hardmode in the Jungle and Underground Jungle. 	1 	
 	During Hardmode in the Corruption and Underground Corruption. 	1 	
 	During Hardmode in the Crimson and Underground Crimson. 	1 	
 	During Hardmode in the Hallow and Underground Hallow. 	1 	
 	During Hardmode in the Snow and Ice biomes. 	1 	
 	During Hardmode in the Desert and Underground Desert. 	1 	
 	During Hardmode in the Jungle and Underground Jungle. 	1 	
 	During Hardmode in the Corruption and Underground Corruption. 	1 	
 	During Hardmode in the Crimson and Underground Crimson. 	1 	
 	During Hardmode in the Hallow and Underground Hallow. 	1 	
 	During Hardmode in the Snow and Ice biomes. 	1 	
 	During Hardmode in an Ocean biome. 	1 	
 	During Hardmode in The Underworld. 	20-50 	
 	During Hardmode, before defeating The Twins. 	1 	
 	During Hardmode, before defeating The Destroyer. 	1 	
 	During Hardmode, before defeating Skeletron Prime. 	1 	
 	During a Blood Moon in Hardmode. 	1 	
 	During Christmas. 	1 	
 	During Halloween. 	1 	
 	During Halloween, from enemies with <20 defense, <40 damage and < loot. 	1 	
 	During Halloween, from enemies with <20 defense, <40 damage and < loot. 	1 	
 	Before Hardmode, after defeating Skeletron, in the Underworld. 	1 	
 	During Hardmode in the Snow biome. 	1 	
 	After defeating any mechanical boss, in the Jungle. 	1 	
 	From any enemy inside the Hardmode Dungeon. 	1 	
 	During Hardmode in the bottom half of the Cavern layer or the Underworld.	1 	
 	When player is below maximum mana. 	1-2 	
 	When player is below maximum health. 	1 	
== Coin drops ==
Most enemies will typically drop a few stacks of coins after dying. Enemies that drop a large number of coins have a higher chance of dropping multiple stacks.
The total amount of money dropped is calculated using a "base value", which depends on the enemy, and in Expert Mode, the "base value" is multiplied by 2.5 and weak enemies receive an additional multiplier to it in Hardmode and after Plantera has been defeated depending on their normal mode stats. A Skeleton, for example, has a "base value" on normal mode of , and on Expert Mode, in pre-Hardmode, in Hardmode, and after Plantera has been defeated. The exact amount of money dropped is this number multiplied by 80–120%.
After the amount of money is determined, there are then a few chances for the number to be increased.
* 20% chance of increasing by 5–10%
* 10% chance of increasing by 10–20%
* 6.67% chance of increasing by 15–30%
* 5% chance of increasing by 20–40%
These increases are not mutually exclusive, are multiplicative, and an enemy may have its money increased several times. It is possible to get all increases at once, as each one is rolled individually. Additionally, the Midas debuff increases the money dropped by 10–49%. The average amount dropped, therefore, is 106.14% of the "base" value, or 137.45% if the enemy is afflicted with Midas. It is possible to get it increased even more by the Lucky Coin.
== Double loot ==
Old-gen console versions of the game give players a chance to have double the loot drop from any enemy. The exact chance of this happening is . Players can easily see the effect when farming for more common loot such as souls or gel. It can be extremely useful if farming for rare items, like the Rod of Discord or Sniper Rifle, as two can be obtained from one kill. However, this obviously requires a lot of luck, as the chance of this occurring is at about 0.5% .
== Despawning ==
Drops on the ground (i.e. not in the player's inventory or in a storage item) will despawn (disappear) upon exiting the world. At that point, it is impossible to reacquire them. If there are more than 400 "loose", dropped items in the world, items will also start despawning. In this instance, the items that have remained on the ground for the longest amount of time may vanish as new items are added to the screen.
== Notes ==
Most item drops are thematically keyed to the enemy that drops them. Some enemies will drop (a version of) their own weapon or magical attack; some drop an accessory which protects against the same debuff(s) they inflict. This last case particularly includes the many components of the Ankh Charm. Bosses and minibosses (notably Biome Mimics) often have a guaranteed drop, or guarantee one item from a list.
== History ==