In One Punch Man, there are classes for heroes, and threat levels for monsters/villains. How does S-Class heroes' power compare to threat levels?
This can be answered from the information in the bonus chapter, Threat Level, in Volume 15.
The threat level and hero rank comparison shown in the chapter are:
- Wolf Level - needs 3 Class-C heroes or 1 Class-B hero
- Tiger Level - needs 5 Class-B heroes or 1 Class-A hero
- Demon Level - needs 10 Class-A heroes or 1 Class-S hero
Disaster or threat levels above demon (dragon and god) were never compared but based on the events in the manga, this might require multiple Class-S heroes, depending on the ability or capability of both the monster and the hero facing it.
There are different threat levels decided upon by the Hero Association. The decision on the threat level depends on
factors such as strength, aggressiveness, and the estimated difficulty in defeating [the monster].
It was also noted in the same chapter that
hero ranks are an imperfect representation of combat ability due to inconsistent factors like battleground conditions and monster compatibility.
This class of heroes was originally created to include characters who can defeat Demon level threats on their own. That said, some of the high ranked S class heroes such as Tatsumaki are capable of fighting Dragon level Threats by themselves or with the assistance of other S class heroes. Another good example is Elder Centipede who is a Dragon Level threat and was defeated by Blast, the first ranked S class hero.