Before fighting the cosmic Garou, the only time Saitama took damage was by a cat. In volume 8 of the manga, in a bonus chapter titled 'Lost Cat,' Saitama is tasked with a mission to find the lost cat, which belonged to one of the hero association's executive daughters.
Saitama vs cat
[ Still trying to do the math on how, the only thing to ever actually damage Saitama in the series is a cat scratching his face.
Serious Punch
This Super Killer Move, just like the other moves, deals 99999 damage to normal opponents, but for another Saitama the damage equivalent is 40000.
As of now, nothing in his universe is able to physically hurt Saitama.
A tragic event forced Saitama not just to get serious, but also to get really, really angry, changing the outlook of One-Punch Man forever. There is one thing that fans of One-Punch Man were waiting for more than anything else, Saitama getting serious, and it finally happened.
He is immortal, so he must live forever... His power isn't all about his body, but he is rather healthy, considering he's still doing his workout, so i reckon somewhere above 100 years, considering he's as normal as everyone else when it comes to basic human things.
That being said, Saitama hasn't used his full power in any of the fights in One Punch Man. However, fans expect him to go all out at some point in the story and are eagerly waiting for the character or the entity that will push Saitama to his absolute limits.
Saitama (1000 IQ) VS 1.000. 000 Colossal Titans: 1.000 IQ, 100 IQ, 10 IQ!
Even if Saitama is able to throw a punch at Rimuru, Rimuru has the ability to regenerate from the damage quickly. As he can easily stop time, Saitama has no chance of fighting against him.
Can Saitama survive a nuke? He can survive a nuclear bomb, probably, sure, but Saitama's fist is a concentrated nuke at minimum power. This would knock Accelerator out instantly just from the sheer surprising force put into the attack overloading his inferior vector changing.
1 One Above All Is The Supreme Ruler Of The Multiverse
If Saitama were to punch him, the blow would not even phase him. In fact, the only way to even weaken One Above All is to cause some form of multiversal imbalance.
If we calculate this distance over time, Saitama speed comes up at 150 9236 miles per second, which is quite close to the speed of light. It's safe to assume that he merely jumped. with no charging up, which means he can be faster. In short, Saitama can travel at the speed of light.
Sometimes the best battle fought is one that isn't fought at all. Light Yagami's Death Note is the ultimate weapon he has with him. Basically, all he has to do is lift his fingers, jot down Saitama's name, and Saitama would be dead.
Saitama is NOT invincible, he took damage from Boros, who is planet-star level.
Despite his nickname, Saitama doesn't always defeat his opponents with a single punch. In fact, occasionally, he unloads a flurry of attacks. As the titular character of One Punch Man, it is often expected of Saitama to finish his enemies in no more than one punch.
8 Saitama's Body Is Resistant To Every Known Attack
Whether it's fire, frost, magic, psionics, weaponry, meteors, he takes them all and emerges without a scratch, with the exception of his destroyed clothes.
Lord Boros is the mirror antagonist to Saitama. Like Saitama, he was too powerful to find a worthy opponent and became extremely bored. Boros serves as a reminder of what Saitama could be if he didn't have a heroic foundation.
Saitama could never be killed by the likes of a gun. He can't be killed by a squared up punch to the back of the head by the fully powered Demon level Deep Sea King, which is mind you, thousands of times more powerful, lethal, or dangerous than any gun.
Unparalleled Strength: Saitama possesses seemingly limitless physical strength and is capable of effortlessly defeating powerful monsters and villains with a single, casual punch (although this strength is not limited to punches). His punches are so powerful that many monsters simply explode when struck.
Goku: 76, even though you might think his IQ could be even lower sometimes, he often proves he can do some smart things too, especially while fighting and especially during DBZ.
Immeasurable Strength: Saitama possesses an immeasurable amount strength and as a result is capable of destroying powerful monsters and villains with a single one punch (though this strength is not limited to punches).
Can Saitama lift 200 quintillion? Gravity is about 1/5th as strong as Earth's on Io, so with a mass of 89.3 x 10^21 kg (half of Io canceling out the one-handedness), Saitama at the time could probably effortlessly lift 16 quintillion tons on Earth.
He exhibits the same strength effortlessly and yet still has more room for growth. At this point, he hasn't ever needed to use his full power, whereas Goku frequently needs to reach his limits. All in all, Saitama wins this competition.
Despite having received God's powers, there wasn't anything Garou could do to defeat the Caped Baldy. Suffice to say, Saitama hasn't lost a single fight in the One Punch Man manga so far.