# What is the most common element in the human body? [closed]

I was wondering that since H2O was 66% of the human body, hydrogen would be the most. But apparently carbon is. Can someone explain that?

## closed as unclear what you're asking by Mithoron, Tyberius, andselisk♦, Melanie Shebel♦, Todd MinehardtMay 4 at 17:48

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• You have to clarify what you mean by most, whether that means number of atoms or by mass percentage. @JacobLee – Tyberius May 1 at 22:33
• And you could take most of the water out of a human body and still have a body (a dead one, admittedly). – matt_black May 2 at 0:20
• I don't think a lack of clarity on atomic vs mass % is sufficiently unclear that the question cannot be answered. – A.K. May 3 at 5:26

## 1 Answer

No, carbon is not the most common element of the human body. The human body is mostly water, so the most common element is bound to be hydrogen or oxygen.

Which one wins depends on the rules of your game. If you are counting atoms in all those $$\ce{H2O}$$ molecules, you choose hydrogen. If you go by mass instead, oxygen is the most common element in our bodies.