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.
Iceman at his peak can freeze atoms. Magneto can tear atoms apart, practically committing nuclear fusion. If he wanted, he could tear the atoms away in Iceman and make him explode (since atoms have their own small magnetic field.) or force his atoms so close together they fuse and creates a large bursts of energy. Even without crazy powers like that, Magneto controls the entire Electromagnetic spectrum. That means micro waves. Magneto could run micro waves around Iceman hot enough to eventually melt him.