what y level do slimes spawn

Slimes spawn in the Overworld in specific "slime chunks" below layer 40, regardless of light levels. They can also spawn in swamp biomes between layers 51 and below, but only when the light level is below 7 and moonlight on that particular night is more than 0. The spawn rate of underground slimes isnt affected by light level. Therefore, the area in which slimes spawn must be below the world height of Y=40. Slimes can spawn under any Minecraft biome except the mushroom fields.