What's the minimum distance between two iron golem farms?

Considering the pretty common design (20x20 base) for the iron golem farms, what is the minimum distance from one golem farm to another to make them work correctly? And how is this "distance" calculated diagonally?

The centers are 63.639 blocks apart (from vector [0, 0, 0] to vector [45, 0, 45] as [x, y, z]) and they are read as two separate village.

There is a good write up on Village mechanics on the Minecraft Wiki. For two villages to be safely treated as separate villages, they need to be greater than radius + 32 blocks away from each other.

Not that the radius is defined as:

• The distance from the center point to the furthest door, -OR-
• 32 blocks

whichever is greater. This means that the radius is always at least 32, no matter what, but it can be more than that if there are any houses further than 32 blocks from the center

So, if your Iron Golem farms are 20x20, and the center of the village is slap bang in the middle of that, then your radius is a further 10 blocks from one side of the farm, (i.e. 30 blocks). However, 30 < 32, so we take radius=32

radius + 32 = (32) + 32 = 64 blocks.

If you are working a lot with villages/golem farms, you might find this mod handy: Village Info Mod. It will help calculate how far you are from the village center, and other useful info.

Straight from the 1.14 code:

protected int villageDistance = 32;

And

protected final int villageSeparation = 8;

Though I don't think distance is checked in later versions.

From what I've seen, the requirements to spawn it is:

1. The villager must be gossiping with another villager
2. The villager has NOT recently slept AND worked
3. The villager has not seen an iron golem recently
4. The villager has a profession
5. 5 villagers within 10 blocks meet those requirements (other than #1).

This is from the yarn deobfusication of Minecraft, I don't see any other requirements in the code.