NPC spawning

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In Terraria, monsters will spawn off camera and pursue the player based on their AI. The rate at which monsters are spawned, the maximum number of monsters, and the type of monster spawned are all dependent on the time of day, biome, the tile type of the ground, and other factors.

Spawn Rates[edit]

There is a 1 in "Spawn rate" chance a monster will spawn every game tick. There are 60 ticks per second, so a spawn rate of 600 means, approximately, a 10% chance of at least one enemy spawning per second, and a spawn rate of 100 means a 60% chance of at least one enemy spawning per second.

When the game is determining the maximum number of enemies in the area, the "Max Spawns" is used. Some enemies count towards this limit more than others. Most bats are considered half an enemy, and teleporting casters typically count as 3. Bosses count as 5. In general, large or special monsters count for more than one spawn.

Note: the "Max Spawns" focuses only on monsters that are in specific area whose center is the player, in other words, active monsters for the player. When a monster is outside the 504*283.5 blocks rectangle (1920*1080 pixels screen multiplied with 4.2*4.2) and it is not the boss, the monster will not be considered active, thus not counted in when checking the max-spawns limit and other calculations. (Fortunately for the monster-farmers: the monster will despawn if it is outside another specific rectangle which is much smaller. More details, go to NPC Despawning)

The minimum (fastest) spawn rate under normal conditions is 60, and the maximum spawns is 15. The modifiers from Water Candle and Battle Potion are set before these limits are checked. Invasions (including Goblin Invasion, Frost Legion, and Pirate Invasion) and moon Events(Pumpkin/Frost Moon) are a special case; they ignore any modifiers or limits to the spawning rates or number of spawns (including water candles/ battle potions).

Drinking the Calming Potion decreases enemy spawn rate.

Biome Spawn rate Max Spawns HM Spawn Rate HM Max Spawns
Surface (day) 600 5 540 6
Surface (night) 360 6 324 7
Surface (Blood Moon) 108 11 97 14
Underground (dirt layer) 300 8 243 10
Cavern (stone layer) 240 9 216 11
The Underworld 600 10 162 15
Jungle (day) 240 7 216 9
Jungle (night) 144 9 129 11
Jungle (Blood Moon) 60 15 60 15
Jungle (dirt layer) 120 12 97 15
Jungle (stone layer) 96 14 86 15
Corruption (day) 390 6 351 7
Corruption (night) 234 8 210 10
Corruption (Blood Moon) 70 15 63 15
Corruption (dirt layer) 195 11 157 14
Corruption (stone layer) 156 12 86 15
Hallow (day) 600 5 540 6
Hallow (night) 360 6 324 7
Hallow (Blood Moon) 108 11 97 14
Hallow (dirt layer) 300 8 243 10
Hallow (stone layer) 165 12 140 14
Meteorite (day) 240 5 216 6
Meteorite (night) 144 7 129 8
Meteorite (Blood Moon) 60 12 60 15
Dungeon (dirt layer) 120 14 97 15
Dungeon (stone layer) 96 15 86 15
Invasions and Pumpkin/Frost Moon 20 10 + 1.5 per player 20 10 + 1.5 per player

Additionally, the spawn rate will be modified by the number of active monsters in the area. The fewer active monsters there are, the faster they will spawn. If there are fewer than 20% of the maximum number of spawns, the spawn rate will be multiplied by 0.6. If fewer than 40% the spawn rate is *0.7, 60% is *0.8 and 80% is *0.9. The spawn rate is sped up even more if below a certain depth or in a corrupted biome.

The presence of friendly NPCs greatly reduces the rate at which enemies spawn, and also reduces the maximum enemies as well. When 3 or more NPCs are present, no enemies will spawn. Special events such as Goblin Invasion and Blood Moon bypass this reduction.

Some biomes will override each other when determining the spawn rate. Corruption, Dungeon, Meteor and Jungle are all mutually exclusive spawn rates. Dungeon has the highest priority, then jungle, corruption, and finally meteor. For example, if a meteor hits the jungle, it will use jungle spawn rates.

Spawning Basics[edit]

Each player in game will spawn their own monsters. If two players are in the same area, monsters will appear twice as fast as they would with only one player. (But Max Spawns rule are still used, which means that even if 2 players are in the same spot, you cannot gather 30 normal monsters near the spot. (Don't forget, the bats count as half a monster, and some special monsters count as 2 or more.))

Choosing a spot to spawn the monster[edit]

Spawn area illustration

When the game decides to spawn a monster, it will first choose a random tile within a rectangle around the player. The maximum distance from the player it can choose from is 84 tiles to the left or right, and 47 tiles up or down. If the picked tile is solid block, it will try another one. If the picked tile has a wall that blocks monsters from spawning, it will also try another tile.

Once an empty tile is found, it moves down until it finds the ground. If there is enough space for a monster to be spawned at this location, this will be the tile it chooses. The exception to this is when the player is in an area where Harpies can be spawned. In this case the game does not attempt to find a ground tile.

The chosen tile is then checked to make sure it is not within the "safe" area around the player. Monsters cannot spawn less than 62 tiles away left or right and about 35 tiles above or below.

Choosing a type of monster to spawn[edit]

The type of monster spawned will depend on many factors including, but not limited to:

Certain events, such as Goblin Invasion, can override or change certain rules about spawning. For example, Goblin spawning will not be stopped by walls that normally prevent spawning.


  • When standing on the left or right edge of the world, the monsters can spawn on screen, as long they are at least 62 tiles from the player. The screen is around 85 blocks wide, so in this case the monsters can spawn in the farthest quarter of the screen.


  • 1.2.4: Fixed bug where spawn rates would increase underground when a moon event is happening.
  • 1.2.3: Fixed bug where spawn rates were higher than intended everywhere rather than when below the middle of dirt layer.

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