Light levels and mob spawning in Minecraft 26.3: the exact rules, and how far a torch really protects

If you learned Minecraft before 2021, you probably learned that hostile mobs spawn at light level 7 or below. That has not been true in the Overworld since 1.18. Today, hostile mobs need block light 0, and that single change affects everything from how many torches you need to how dark a mob farm has to be.

This guide gives the exact rules for Java 26.3, with the numbers you need for spawn-proofing a base and for building farms that actually spawn.

Diagram: SyntaxMine.

Quick answers

• What light level do hostile mobs spawn at? In the Overworld, only at block light 0, with an internal sky light of 7 or less. Any block light at all, even level 1, stops them.
• What light level do animals need? 9 or more when the block is not open to the sky, and they spawn on grass.
• Do spawners care about light? Less: a mob spawner works up to light level 11.
• How far apart should torches be? A torch gives light 14 at its own block and loses 1 per block of walking distance, so it keeps every block within 13 blocks of walking distance at light 1 or more. That is far further than most people space them.

How light works

Minecraft has 16 light levels, from 0 to 15, and two kinds of light:

• Block light comes from light sources: torches, lanterns, glowstone and so on.
• Sky light comes from the sky. It is 15 in the open, travels straight down through transparent blocks without weakening, and loses 1 per block when it spreads sideways or upward. How much of it counts depends on the time of day.

Block light drops by 1 for every block of taxicab (walking) distance from the source. Diagonals cost two steps, not one, so light spreads in a diamond shape, not a circle.

Light levels of common sources

The spawning rules

Hostile mobs (Overworld)

Two conditions, both required:

1. Block light must be 0. Changed in 1.18. Before that, hostile mobs could spawn at block light up to 7.
2. Internal sky light must be 7 or less. In practice: at night in the open, or anywhere covered.

This is why a cave or a dark room spawns mobs, and why a single torch in a room is enough to stop spawns for a long way around it.

Animals

Passive mobs need light level 9 or more when the block is not exposed to the sky, and they spawn on grass blocks. That is why animal pens under a roof need proper lighting.

The exceptions

• Mob spawners keep spawning up to light level 11. Lighting the room around a spawner reduces it but you need a lot of light, or block the spawner itself, to stop it.
• Slimes spawn in swamps based on the moon phase, and in slime chunks underground, with their own rules. See the slime farm guide.
• Drowned spawn in water with their own conditions; the trident farm guide covers them.
• Sulfur cubes spawn in sulfur caves at any light level, so torches do not stop them at all (sulfur cube guide).
• The Nether and the End have their own rules, not covered here.

Spawn-proofing a base

Because hostile mobs need block light exactly 0, spawn-proofing is easier than it used to be:

• Every floor block needs light 1 or more. Not 8: 1.
• A torch covers 13 blocks of walking distance in every direction. Placing torches in a grid roughly 13 blocks apart along each axis leaves no block at light 0 on flat ground. Walls, holes and steps add distance, so check corners.
• Use F3 to check a doubtful spot: the debug screen shows the light level at your position.
• Or deny the spawn space entirely. Hostile mobs cannot spawn on bottom slabs or on glass, so a slab or glass floor is spawn-proof whatever the light.

Building mob farms: make it truly dark

The flip side of the rule: a single light leak kills a farm. Because any block light above 0 blocks hostile spawns:

• Seal every spawning floor completely. One gap in the roof or wall at night, or one light-emitting block (including some decorative ones), and that area stops spawning.
• Watch for light from below and the sides. Light travels through transparent blocks and around corners.
• Light the surroundings instead. Every dark cave around your farm competes for the same hostile mob cap. Lighting caves within the spawning range (24 to 128 blocks from you) pushes more spawns into your farm.

The dark-room mob farm and the XP farm guide use exactly these rules, and the mob spawner optimizer helps you size the spawning area.

Frequently asked questions

What light level stops mobs from spawning?

In the Overworld, any block light of 1 or more stops hostile mobs, since 1.18. They need block light 0 to spawn.

Do mobs still spawn at light level 7?

Not in the Overworld in current Java. That was the rule before 1.18. Now hostile mobs need block light 0.

How far does a torch stop mobs spawning?

A torch is light 14 and loses 1 per block of walking distance, so every block within 13 blocks of walking distance stays at light 1 or more, where hostile mobs cannot spawn.

What light level do animals spawn at?

9 or more when the block is not open to the sky, and they spawn on grass blocks.

Do torches stop spawners?

Only partly. Spawners work up to light level 11, so you need much more light, or to block the spawner, to stop it.

Can mobs spawn on slabs?

Hostile mobs cannot spawn on bottom slabs or on glass, so those floors are spawn-proof at any light level.