Jor-El says in Superman I that Kal-El will not be like the humans of Earth. That he will have super strength and that he will be much denser than a man. Being denser means you have more mass which means you are heavy relatively speaking compared to a man. How heavy is Clark then as he is walking around? I never noticed cars he got into dragging on the ground or anyone saying he was made from carbon nano-tubes.

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    He meant denser as in not able to understand jokes. Notice that you never see Superman laugh yet he can hear EVERYONE fart. Commented Jan 2, 2013 at 15:27
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    @KevinHowell true he was a square for sure Commented Jan 2, 2013 at 16:39
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    density and mass are important to the laws of physics, and therefore do not apply to superman Commented Jan 2, 2013 at 21:20
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    I would say 636 lbs. I'm using this measurement of steel as reference. lol. metrosteelfl.com/beams.html
    – user15383
    Commented Jun 21, 2013 at 2:45
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    That's part of the original explanation of his power before he became pretty much magic ^.^
    – Durakken
    Commented Sep 17, 2016 at 21:48

5 Answers 5


Lois Lane interviewed Supes in the movie Superman. Excerpt:

LOIS: And how big are you? How tall are you?

SUPERMAN: About six four.

LOIS: And, uh, how much do you weight?

SUPERMAN: Around two twenty-five.

It's possible that since Superman can counteract the force of gravity with his power, his weight might be one that he assumes to avoid damaging people or property that might collide with his real and presumed higher mass. But in the movie Superman Returns, Superman is rendered unconscious by extreme exertion and exposure to green kryptonite. During his unconsciousness Superman is moved on a gurney with expected effort by ordinary humans and laid upon a hospital bed, which does not collapse under his weight. If we assume that Superman is not levitating when unconscious, then his mass cannot be more than a few hundred kilos else he would have destroyed his hospital bed and gurney.

  • +1 but do you think that really makes sense? Kal-El was just wrong then? Density by definition has to do with how much mass an object has. If Superman is very dense, then this Superman is not telling the truth in that interview. Good quote for sure. Commented Jan 2, 2013 at 3:34
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    Lois asked about weight, not mass, so Supes could still have been telling the truth. If you can counteract the force of gravity (fly), then you can adjust your perceived weight. Clark Kent and to some extent Superman would need to do this to avoid breaking furniture or injuring people he happened to bump against.
    – Kyle Jones
    Commented Jan 2, 2013 at 3:42
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    225? What unit?
    – user931
    Commented Jan 2, 2013 at 8:16
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    He's a reporter, not a scientist. "Pounds, what other units are there?"
    – Plutor
    Commented Jan 2, 2013 at 22:23
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    225 pounds isn't big. Many WWE buddies have greater mass. I thought its Kg.
    – user931
    Commented Jan 3, 2013 at 6:06

"Much Denser Than a Man"

Plausible Explanation

While density refers to mass/volume, it could be that he was referring to something on a different scale than you were thinking. Density normally means mass/volume. However Population Density doesn't refer to the mass of all the humans per section of volume. That would be stupid. It refers to the # of people per area. Completely different. So my thought not fact, just a plausible explanation Jor-El could have been referring to a protein density, or a cellular density. If this is true then Cal-El, or Clark Kent, or Superman is made up of lighter-weight, closer packed, (and obviously stronger inter-bonded) make up of cells and proteins. That way he's "denser" but he's not heavier.

Number of cells/proteins per volume rather than mass/volume. #IMJUSSAYIN!

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    I applaud your effort for trying but Kyle pretty much bagged it. The writing on Superman missed this little tidbit. It just doesn't make sense. To me, Superman should be as heavy as uranium or mercury at the atomic level and possibly radioactive. Commented Jan 2, 2013 at 6:48

The gravity force of Krypton is an important data here. If we want to measure the physical strength of a humanoid from another planet we need to examine how gravity force will affect it. A far greater gravity force will require human-like bodies to have denser bones and muscles in order to avoid being smashed by it, this heavier body building will surely be a big part in Jor-El superhuman strength.

We can only assume a certain mathematical correlation between gravity and body density, however, it could serve as an approximation to the actual mass of superman on Earth. If we take a weight of 220 lbs. as something plausible for a muscular 6'4'' earth man, it would be feasible that one humanoid of same size from a planet with twice as gravity force as the Earth would weight about 440-450 lbs.

I've not found references to Krypton's gravity force, but Wikipedia suggest it as "massive" comparatively to the Earth, wich suggest that Superman would probably weight several metric tons on Earth (and it would easily explain why he's so strong and thought).

Why he lies about his weight and why the movies and comics fail to represent the fact of such a weight is only because neither movies nor comics pretends (or can) be exhaustively correct at a physics level, for both, narration and resources reasons.

  • So it would be like one of us living on the moon and buildings are made out of styrofoam but the whole air breathing thing still confounds me. Commented Jan 2, 2013 at 17:20
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    I really wouldn't expect things like bone density to scale linearly with planetary gravity. Doubling gravity would have all sorts of subtle effects on physiology, many of which would depend on things like bone surface area and muscle volume, which would scale as the gravitational force squared or cubed. Commented Jul 10, 2014 at 16:14
  • You're approaching it from the wrong angle, someone young enough to remember their physics please calculate the minimum mass of a 6'4 human required to at minimum stop a speeding bullet... I suspect the weight is much higher than double or triple a regular 6'4 guy's
    – ycomp
    Commented Mar 31, 2016 at 6:20
  • @ycomp If you're standing still you'll be pushed back by a bullet no matter how much you weigh. If you weigh 225 lbs then at typical muzzle velocities you'd need to be moving forward at least 17 mph to stop a bullet (at 850 ft/s, 90gr). If you weighed a half-ton you could drop that to 8 mph. Of course if you were further away than point-blank range, or had a different muzzle velocity or bullet weight the results would differ.
    – Charles
    Commented Jan 23, 2018 at 1:51

maybe he is atomically denser but composed primarily of undiscovered elements? or; as he already emits anti-gravitons perhaps they are somehow lattice bound into his atomic structure? or to go realllllyyyy meta perhaps kryptonians employ some unknown quantum principle involving gluons and photons somehow being transformed automatically into gravitons by kryptonian cells and their brain chemistry simply allows them to control the extent to which this takes place, enabling flight (this would make them much more atomically dense without being to much heavier than an average human as their cells may be able to independently regulate their own mass given a specific gravitational field) although this would give rise to many more problems for the cloning storylines... no evidence to support this just one more theory to add to this list...

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    Welcome to SFFSE! Do you have any evidence to support your arguments? Commented Aug 27, 2015 at 5:57
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    At present this reads like fan-fiction/headcanon. If you can back this up with evidence that supports your theories, I'm happy for it to remain, if not then I will be forced to remove.
    – Valorum
    Commented Aug 27, 2015 at 7:45
  • This is why I don't bother trying to answer. Research for this site is way harder than research for StackOverflow.:P
    – zer00ne
    Commented Aug 30, 2015 at 1:05

Density - a measure of the amount of information on a storage medium

The human storage medium for a single cell is DNA. Two strands in a twisted bond of 26 chromosomes.

Superman has more. How much? Well enough to be considered "denser" than humans. So much more, a single cell of his body has the capacity to process the suns energy into radiant energy that his body can:

Heat vision - Focus energy to a single point and then project it out.

create a shield of force around his body that can be extended slightly beyond its periphery...like a suit of armor. Force field that he can contract or expand and seem like he has super strength.

fly - warp local space to create gravity

freeze breath - draw energy from the air to cool it and funnel it in a specific direction (opposite of heat vision)

Super hearing - filter out sounds or magnify others

Basically, his body is normal but it's the manipulation of the the suns energy that allows him his "gifts". The problem is Superman isn't into researching what his body can do. He just uses it like a hammer instead of treating it like a fine machine.

At least, that's how I would do it.

Kal El radiates this energy around him creating a protected environment as he is alien to earth's atmosphere and needs to filter it. His radiant environment filters out viruses, bacteria, fungus and anything else that would harm him. That is why he was constantly sick as a child. It wasn't until puberty began that his body began to create the protected environment as it is now. It is also why kryptonite is bad for him. It absorbs that radiant energy he gives off, converts it and then radiates it back out. Which does havoc to his biological systems.

Want to remove that power from superman? Simple, convert his "DNA' or whatever to a version that does not convert the sun energy to radiant energy. Then he would be...

just another man.

I thought Joe and Jerry explained all this?


  • This seems like an improbable interpretation. Where are you getting this from?
    – Adamant
    Commented Jan 5, 2017 at 2:19
  • Agree with @Adamant, this interpretation seems quite tenuous, is there any evidence in any superman material to indicate this is the density being discussed? Density by default normally refers to physical density.
    – Jack
    Commented Jan 5, 2017 at 2:34
  • "This is why [Superman] was constantly sick as a child." I would be very interested to hear more about that part since I don't think I've ever heard that before. Commented Apr 30, 2020 at 22:40

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