what light level do mobs spawn

Hostile mobs in modern Minecraft only spawn in very low light: they need block light level 0 to appear from normal (natural) spawning.

Here’s the quick breakdown:

• For random hostile mob spawning (zombies, skeletons, creepers, etc.) underground or at night:
  • They require block light level 0.

* Any artificial light source (torch, lantern, etc.) that raises block light to 1 or higher will prevent those spawns on that block.

• Sky light (from the open sky) is tracked separately:
  • High sky light (around daytime outdoors) also prevents hostile mob spawns; mobs mainly appear where sky light is low (night, caves, under trees, overhangs).

• For mob spawners (the cage blocks in dungeons):
  • Their behavior can differ from normal random spawning and can be affected by difficulty or specific rules, but players generally still “spawn‑proof” them by keeping the area very bright (high light levels around the spawner).

So, in practice: if you keep every block in your base at block light level 1 or higher (with torches or other light sources), random hostile mobs will not spawn there.