Board Thread:Questions and Answers/@comment-32849902-20170813202826/@comment-29662163-20180327205648

An accepted rule of thumb is, to be "infinite" in any sort of way, you need to be a transcendental being (god-esque entity), what Saitama is not. Actually, based on his current feats alone, he's not anything special. All we know is that he can hit hard enough to go a bit above baseline planet-busting, his fastest speed shown is about 5-10% speed of light, and he can tank hits that are about as hard as his own hits.

There are many a ways to kill/defeat Saitama. Heck, even a character from a much weaker verse could do it. All Saitama has is a lotta strength, but almost no hax or hax resistance.