I looked on Wiki and for the most part like how the EP values correlate with the ranks. I just wanted to make some minor changes to better fit my fanfiction.
I added G rank because I felt that regular animals should have their own class below goblins. Also, it can be used for children and baby monsters before they become powerful. I also adjusted the values for some of the ranks so that they are more even.
I also added an SSS class for the superpowers being Guy, Milim, the true dragons and all the other beings that should have their own group. I also wanted to add a level in between the superpowers like Guy and unawakened demon lords for those who are really strong, but just not on the same level. Also, since anyone who declares themselves a demon lord would be bumped up to S rank, even if they're not actually in that rank, it felt fitting to put that third rank.
The monsters that were categorized within a certain rank by the original author will stay that rank. Its just the numbers that are changed.
Note: This may be subject to change
SSS (Annihilation class): 100,000,000+
SS or Special S (Catastrophe class): 10,000,000+
S(Disaster class): 1,000,000+
Special A or S- (Calamity class): 500,000+
A+(Hazard class): 200,000+
A: 100,000+
A-: 15,000+
B+: 10,000+
B: 8,000+
B-: 6,000+
C+: 3,500+
C: 2,500+
C-: 1,500+
D: 1,000+
E: 250+
F: 50+
G: Less than 50
A major rank difference will mean 1 letter apart. (i.e. A to B, C+ to B+)
A minor rank difference will be 1 sign apart. (i.e. C to C+, B+ to A-)