How chance for equipment is calculated
This is actually an answer to a question that arose in another thread.
If maths gives you a headache you might want to look away now.
Weighting
Simple 32, Usual 16, Unusual 8, Rare 4, Epic 2, Legendary 1
Calculation
Add the weightings for each level of material, work out the total, convert to a percentage
The simplest example
You are making a piece of equipment that needs 4 materials, you have 3 simple and 1 rare
3 simple 32 + 32 + 32 = 96
i rare = 4
Total = 96 + 4 = 100
% Simple = 96/100 x 100 = 96% % Rare = 4/100 x 100 = 4%
Another simple example
You are making a piece of equipment that needs 4 materials, you have 1 epic and 3 legendary
1 epic = 2
3 legendary 1 + 1 + 1 = 3
Total = 2 + 3 = 5
% epic = 2/5 x 100 = 40% % legendary = 3/5 x 100 = 60%
This works for Standard and Invader's Equipment. I don't have the things required to check Shaman and Special equipment.