The Superhero Database Classification number, or SHDB Class, is a number that represents the overall 'power' of a character. All traits of a character are used for calculating the Classification.
What it DOESN'T mean
This doesn't mean that a higher class would always beat a lower class character. But the bigger the difference in Class is, the more obvious it is who'll win in a fight.
How is this calculated
( INT^1.3 + (STR*0.5 )^2 + (SPE*0.5)^2 + DUR^1.6 + (POW + (SPS*SPL))^2 + COM^1.8 ) ^ TIER
Super Power Score and Level
Every Super Power has a score (SPS) that is used to calculate the Class. Each Super Power also has 3 levels (SPL). The level is set when connecting that Super Power to a character. The level determines the final score, of the Super Power, being used in the calculation.
I mean the dude can also be a nightmare fuel for curses since he can just erase them with a touch, and that includes sukuna himself, unless he had a physical body.
And I'm gonna add, that based on the stats, you're underestimating touma too much, lol.
And also that isn't all of his powers, if I may also add again, he has more shit that can destroy the whole world (planetary) and beyond. (Universal)
From what we've seen in jjk so far, no one is nowhere near planetary, except for maybe yuki because of her black hole, but I kind of doubt it too.