We know a soul has weight [that is, one can prove a soul has physical weight, for example 21 grams].

A Soul Weighs 21 Grams? Does a Soul Have Weight?

There is no scientific evidence that shows that living beings have souls or that a soul has weight. However, the notion that a soul has weight (specifically 21 grams) does come from a scientific study.[1][2][3]

Duncan Macdougall – 21 Grams Theory.

Physician Duncan MacDougall published a a study in 1907 that concluded that a soul (or in his own words “soul substance”) may have weight. Specifically, the study to some extent implied that a soul might weigh “three-fourths of an ounce” or 21.3 grams.

This data was gathered from a limited set of people in a nursing home who were weighed upon their death by MacDougall.

While his findings did show that a few patients lost weight upon death, and one lost 21.3 grams specifically, the results were a bit all over the place. Ultimately only one of the 6 patients weighed lost the famed “21 grams.”

Further, and somewhat disturbingly, MacDougall also allegedly poisoned 15 dogs and weighed them to test his theory… and none of them lost weight. This led MacDougall to conclude dog’s didn’t have souls (🙄).

Given the limited sample size, the fact that only one result matched exactly, and that one of its conclusions was “dogs don’t have souls”… it is safe to say that this study does not act as evidence of the weight of the soul.

Further study would be interesting, but I could not find one in my research. Thus, assuming I’m not missing a more conclusive study, the idea that a soul for sure has weight has to be filed under “inconclusive at best” (and thus it has to be admitted that we don’t have proof that a soul has weight).

With that covered, actually did a good breakdown of this subject. I have to be honest, I wanted to know the answer to this one, but I don’t care much to dive into the weight of dead bodies. So with that in mind, check out the article on the weight of a soul. 🙂

Does the soul weigh 21 grams?.

FACT: “According to the Egyptians, after you died the god Anubis would put your soul on one side of a giant scale and he would put a feather on the other side. Then Thoth would decide where you should go. The more bad things you had done in your life, the heavier your soul would be. If it was heavier than the feather, then you would have to go to the bad place. But if your soul was lighter than the feather, then you could go to the good place.” – So perhaps the dogs were just very good boys, but the humans were more complex. <—- joking, just adding some humor to an otherwise “heavy” subject.


We don’t know that a soul has weight, therefore it is incorrect to claim that “we know a soul has weight.” A soul may have weight, or there may not be such a thing as a soul. If there is such a thing as a soul, it may not have a physical weight.

Given these details, I have labeled the idea that “a soul has weight” as a myth. This shouldn’t be though to imply that “a soul does not have weight” but simply that “the claim that we know a soul has weight is false.”


  1. MacDougall, Duncan (1907). “Hypothesis Concerning Soul Substance Together With Experimental Evidence of the Existence of Such a Substance.”   Journal of the American Society for Psychical Research: 237.
  2. 21 Grams Experiment.
  3. 21 Grams – The Experiment to Find the Weight of the Soul.

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