1 - Light source
Emits light level 14, safe out to 13 blocks (taxicab).2 - Spawn rules
Since 1.18 hostile mobs need block light exactly 0, so any block light of 1 or more is safe.
3 - Layout and spacing
Max safe spacing for this source: 13 square, 18 staggered.
Verdict
Fully spawn-proofed at 13 blocks apart
Every floor block in range stays at block light 1 or higher, so nothing spawns. You could space the grid up to 13 blocks and still be safe.
Floor light coverage
25 x 25 block floor, top down. Coverage 100.0%.
The numbers
Hostile mobs on the overworld spawn only on a block with block light 0, so placing enough light to keep every reachable floor block at light 1 or higher stops them completely. Light drops by 1 for each block of taxicab travel, so a torch of level 14 protects everything within 13 blocks. Space torches up to that distance in a grid, or wider in a staggered pattern, and no mob can spawn.
The spawn check in the game reads the block light at the spot a mob would appear and compares it to the dimension's spawn light limit, which is 0 on the overworld. If the block light is above the limit the spawn is rejected, so even a single point of block light is enough to block it. This is a hard rule, not a probability: a block at light 1 will never spawn a hostile mob, no matter the time of day or sky light.
The calculator above takes a light source, applies the exact taxicab falloff, and shows the safe radius plus the widest spacing that still covers every block. The heatmap marks any cell that drops to the spawn limit in red so you can spot gaps before a creeper finds them.
The safe radius is the source's light level minus 1 (since you need block light 1 to be safe on modern versions). A square grid can be spaced up to that radius; a staggered layout, where every other row shifts by half a spacing so the diamond-shaped light patches interlock, covers the same floor with fewer light sources spaced further apart. These spacings are computed for the modern (1.18 and later) block-light rule:
| Light source | Light level | Max square spacing | Max staggered spacing |
|---|---|---|---|
| Lantern / Glowstone / Sea Lantern | 15 | 14 | 19 |
| Torch / End Rod | 14 | 13 | 18 |
| Soul Torch / Soul Lantern | 10 | 9 | 12 |
| Redstone Torch | 7 | 7 | 8 |
| Magma Block | 3 | 3 | 3 |
Before 1.18 the threshold was block light 8 rather than 1, which roughly halves every spacing in this table. Use the Before 1.18 toggle in the calculator if you play on an older version or a server pinned to one.
You do not always have to light an area to spawn proof it. The spawn check also needs a valid block for the mob to stand on, so covering a surface with slabs, carpets, buttons, or other blocks mobs cannot spawn on stops spawns without any light at all. This is the cleanest way to spawn proof a build where you do not want visible torches everywhere.
For large open areas, lanterns hung from the ceiling or sunk into the floor on a wide grid are the most efficient lit option, and the staggered spacing from the table keeps the torch count down. Combine both approaches: light the open ground, and slab over the awkward ledges and corners the light cannot reach.
Since 1.18, torches keep mobs out within 13 blocks (taxicab distance), because a torch is light level 14 and you only need block light 1 to block spawns. In a square grid you can space torches up to 13 blocks apart. In a staggered pattern, where every other row is offset by half a spacing, you can go up to 18 blocks apart with full coverage. Before 1.18, when you needed block light 8, the same torch only reached 6 blocks, so torches went roughly every 6 to 7 blocks.
Since Minecraft 1.18 hostile mobs on the overworld require block light exactly 0 to spawn, so any block light of 1 or higher guarantees no hostile spawn on that block. Before 1.18 the threshold was block light 7 or lower, so you needed block light 8 to be safe. Sky light and the time of day do not change this block-light rule, which is why fully enclosed dark rooms still need light placed inside them.
Block light spreads outward one block at a time and drops by 1 for each block of travel, measured in taxicab distance (the sum of the horizontal and vertical block steps, not a straight line). So a torch of level 14 gives light 13 one block away, 12 two blocks away, and so on, reaching 0 at 14 blocks. Walls and solid blocks force the light to travel around them, which shortens its reach in enclosed spaces.
Yes. The block-light 0 rule applies everywhere on the overworld, so any unlit cave, tunnel, or dark corner within loaded chunks can spawn hostile mobs and feed the mob cap. Spawn proofing a base means lighting the surrounding caves and dark spots too, not just the floor you stand on. Slabs, carpets, and other partial blocks placed on a surface also stop spawns regardless of light.
Light level 15 sources such as lanterns, glowstone, sea lanterns, shroomlight and froglight cover the widest area, reaching 14 blocks and allowing the largest torch spacing. Torches at level 14 are nearly as good and far cheaper. For a hidden look, you can spawn proof without any light at all by covering surfaces with slabs, carpets, or other blocks mobs cannot spawn on, since the spawn check also requires a valid block to stand on.
Usually a few blocks are still at light 0 between the torches, especially at the corners of a wide grid, or there are unlit caves nearby. Use the heatmap above to find the dark cells, then tighten the spacing or add a torch. Remember that light travels in taxicab distance and gets blocked by walls, so a torch around a corner may not reach as far as you expect.
Planning a mob farm instead of blocking spawns? Check the spawn ranges, or browse more Minecraft tools:
