What is the math behind the Rescale Factor?

[Deltac]

I'm clueless as to how to properly calculate what the scale of a part will be after adjusting the rescale factor.

For exampe: A 3 meter part in modeler program with default rescale factor of 1.25 becomes a 3.75 meter part in KSP. I want to increase the size of the part to 5 meters. Math: 5 divided by 3 = 1.66666somany6's. 3 * 1.6666666 = 4.99999(close enough).

Set rescale factor to 1.66666, reload database, part is now bigger than 5 meter.... wat

I tried searching for the comprehensive guide for rescale factor... and nothing. I'm sure there's something in a thread somewhere, but I want a thread dedicated to this unwieldy thing called rescale factor.

I also don't know where this thread would belong since it involves modifying the game, but it's not talking about any add-ons.

[NathanKell]

If part uses MODEL nodes:

final scale of model will be orig_size * scale_in_MODEL_node(default: 1.0,1.0,1.0) * rescaleFactor * rescaleFactor

*unless* (a) the part is the root part and ( you revert to launch, in which case rescaleFactor is multiplied in only once.

If part doesn't use MODEL nodes:

final scale of model will be orig_size * rescaleFactor.

In all cases if rescaleFactor is unspecified it defaults to 1.25.