How light works, in one formula
Every light source has a strength (torch 14, lantern 15) and light drops by 1 per block of distance. A hostile mob needs light level 0 to spawn — so your job is making sure no floor tile is more than (strength − 1) blocks from the nearest source. The calculator runs that grid math for your spacing.
Spacing rules of thumb
With torches (strength 14), spacing of 12 blocks or less keeps the darkest point at level 2 or higher. Lanterns (15) buy you one more block. For wall-mounted torches remember height counts as distance too — a torch 2 blocks up reaches 2 fewer floor tiles.
From calculator to build
Walk the perimeter counting blocks between planned torches before placing anything — reworking a torch grid after the floor is done is the classic wasted evening. Pair this with our light level & mob spawning guide for the spawning rules, and the XP calculator if you are lighting a mob farm’s kill floor instead.
Why light level 0 is the number that matters — and which light source gives you what — is covered in the light level and mob spawning guide.
The rule in one line
A torch emits light level 14 and light falls by one for every block it travels. Since Java Edition 1.18, hostile Overworld mobs need a block light level of 0 to spawn — not "dim", but literally zero. Any block that receives even light level 1 is safe.
That produces a straightforward spacing rule: a torch keeps everything within 13 blocks safe, because at 13 blocks the light is exactly 14 − 13 = 1. In a straight open tunnel two torches can therefore sit up to 26 blocks apart with no dark gap between them.
Older guides say "a torch every 12 blocks". That advice comes from the pre-1.18 rule, when mobs spawned at light level 7 or below. It is no longer the reason for the number, although it remains a sensible conservative spacing in a room with corners.
How far a torch actually reaches
| Light level at the block | Distance from the torch | Can a hostile mob spawn? |
|---|---|---|
| 14 | 0 blocks | safe from spawning |
| 13 | 1 blocks | safe from spawning |
| 10 | 4 blocks | safe from spawning |
| 7 | 7 blocks | safe from spawning |
| 6 | 8 blocks | safe from spawning |
Level 14 is the torch itself. Every block of travel drops the level by one, so light level 1 is reached 13 blocks away and level 0 — the only spawnable value — is 14 blocks out in open air. In practice walls, slabs and stairs block the light far sooner, which is what makes corners the real problem.
Worked spacing examples
A 100-block straight mine tunnel
Tunnel height 2 and nothing in the way, so the maths is open-air. With 13 blocks of safe radius per torch you can space them 26 apart and need five torches for the whole run. Placing six at 20-block intervals costs one extra torch and gives light level 4 at the darkest point, which is far more comfortable to mine in than level 1.
A 15 × 15 room
Rooms break the open-air assumption because the walls stop the light. Treat the room as needing a torch roughly every 12 to 14 blocks in each direction: four torches on the walls of a 15 × 15 covered room is generally enough, and the corners are the first places to check.
A cave with pillars and overhangs
Every opaque block casts a shadow, and a shadow behind a pillar can sit at level 0 even when the space next to it is bright. This is the case where you ignore the radius entirely and light on line of sight — if you cannot see a torch from where you are standing, place one there.
Bedrock is a different target
Java 1.18 made hostile mobs require block light 0, so any light at all is enough. Bedrock's spawn rules are less strict about that, and the widely used safe target there is to keep every block at light level 8 or higher. With a torch at level 14 that means at most six blocks of spacing in a clear line — roughly half the Java distance. If you are building on Bedrock, size the spacing from 8, not from 1.
The dark spots people always miss
- Under overhangs. Light from above does not bend underneath a roof, bridge or floating platform. The floor below can sit at zero while everything around it is bright.
- Behind large decoration. A fireplace, a chandelier or a wide tree casts a shadow one or two blocks deep that a single torch will not fill.
- Beneath low ceilings. A cramped space compresses the light gradient, so the level drops to zero within a few blocks of the torch.
- Corners and pillars. The classic cause of a spawn inside a base that "has torches everywhere".
- Assuming a torch lights the ceiling. Torches cannot be attached to the underside of a block at all — there is no ceiling torch, which is why lanterns exist.
If you cannot check light levels directly, placing a few extra torches always costs less than dealing with a creeper inside your base.
Lighting a base without rework
The whole point is to count the spacing before placing anything, because redoing a torch grid after the floor is done wastes an evening. These are the items for a long building session.
- Gaming mouse — Placing torches along a measured perimeter is repetitive precision; a good mouse keeps it steady.
- Mechanical keyboard — Walking the perimeter and tallying blocks between torches is keyboard-heavy; reliable rollover helps.
- Second monitor — The spacing rules and the calculator stay open while you build, which is easier on a second screen.
- Desk lamp — Lighting work is done at night in a dark room; a lamp keeps your own notes legible.
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Sources and standards
Where these figures come from
Every figure on this page is computed from the published reference below rather than copied from another calculator.
- Minecraft Wiki — the block light scale, the light level of a torch, and the list of mobs that require block light 0 to spawn.
- Minecraft Wiki — torch light level 14 and the placement rules that decide where a torch can attach.
- Minecraft Wiki — the 1.18 change to hostile mob light requirements and the difference between block light and sky light.
Figures, formulas and reference tables last verified: 24 September 2026.
