The wiki says normal spiders need a 3x3x2 area to spawn, I was wondering how true this is?

I've noticed them spawn in areas 2x2x2? Any help is appreciated.

Source: https://minecraft.wiki/w/Spider

UPDATE: Image of spiders spawning http://postimg.org/image/67bo9lkh1/

  • 1
    Can you verify that it spawned in a 2x2x2 area? Maybe a screenshot?
    – LTPro
    Jul 26, 2013 at 11:26
  • Sure, im trying now. :)
    – John
    Jul 26, 2013 at 11:45
  • I've added a screenshot link. I'm sure I'm just understanding it wrong.
    – John
    Jul 26, 2013 at 12:01
  • Can you clarify what your question is? At the moment it looks like a statement of fact, which is difficult to answer.
    – toryan
    Jul 26, 2013 at 12:47

1 Answer 1


The 3x3x2 spawning requirement is referring to the empty space. Spawning only requires a solid block under the spawn area.

Light level of 7 or less, 3x3x2 space on solid blocks (spawns only on top of the central block). Top half of space may be occupied by transparent blocks (glass, etc.).

This means that the requirement is a 3x3x2 area of empty space with a solid block under the middle empty block. With that in mind, it is easy to see numerous valid spawning locations in your screenshot.

  • Yes that clears it up, that's why they spawned on a 2x2 because they see the air block as valid empty space. Thanks
    – John
    Jul 26, 2013 at 12:55
  • Spiders are, IIRC, 1.4 meters wide. So, when spawning in the center of block, they need 20cm of each surrounding block to be free - they may spawn on a block between two fences (this is an idea, not a fact).
    – Orc JMR
    Jul 26, 2013 at 13:02
  • @OrcJMR The 3x3x2 requirement prevents that, since the fences don't count as the necessary air blocks. Jul 26, 2013 at 16:08
  • @SevenSidedDie While Spider page on the wiki states this 3x3x2, algorithm on Spawning page does not mention the requirement for Air blocks, only "non-opaque" and "must not be obstructed". Sooo I went ahead and did it: i.imgur.com/OCysloW.png Spiders spawn next to fences.
    – Orc JMR
    Jul 26, 2013 at 17:26
  • @OrcJMR Oh, that's interesting. The "must not be obstructed" is usually understood to mean that non-air, non-full-block blocks prevent spider spawning, and it's true of things like slabs, but apparently not fences. I know signs prevent spawning when they are on every block, but maybe replacing those fences with signs would still let spiders spawn... Jul 26, 2013 at 17:32

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