The ten most abundant elements in the human body (by mass) are:

  1. Oxygen
  2. Carbon
  3. Hydrogen
  4. Nitrogen
  5. Calcium
  6. Phosphorus
  7. Potassium
  8. Sulfur
  9. Sodium
  10. Chlorine (chloride)

Below is a quick, high‑yield breakdown.

Quick Scoop: Top 10 Elements

These ten elements together account for virtually all of your body weight, with the first four alone making up about 96% of body mass.

  • Oxygen – Most abundant, largely in water and organic molecules.
  • Carbon – Backbone of all organic molecules (proteins, fats, carbs, DNA).
  • Hydrogen – In water and most organic compounds.
  • Nitrogen – Key for amino acids and nucleic acids (DNA, RNA).
  • Calcium – Main component of bones and teeth, also for signaling and muscle contraction.
  • Phosphorus – In bones, ATP (energy currency), and DNA/RNA.
  • Potassium – Major intracellular ion, important for nerves and heartbeat.
  • Sulfur – In certain amino acids, crucial for protein structure and metabolism.
  • Sodium – Major extracellular ion, controls fluid balance and nerve impulses.
  • Chlorine (mostly as chloride) – Balances charge and pH, part of stomach acid.

By Mass: Approximate Order

Different sources give slightly different percentages, but a common pattern for an average adult by mass is:

  1. Oxygen – roughly 60% of body mass
  2. Carbon – about 18%
  3. Hydrogen – about 10%
  4. Nitrogen – a few percent
  5. Calcium – around 1–2%
  6. Phosphorus – about 1%
  7. Potassium – a fraction of a percent
  8. Sulfur – a fraction of a percent
  9. Sodium – a fraction of a percent
  10. Chlorine – a fraction of a percent

These values vary slightly between references and individuals, but the ranking is consistent.

Simple HTML Table (by Mass)

html

<table>
  <thead>
    <tr>
      <th>Rank</th>
      <th>Element</th>
      <th>Approx. % of body mass</th>
      <th>Main roles</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>1</td>
      <td>Oxygen</td>
      <td>~60%</td>
      <td>Water, organic molecules, cellular respiration</td>
    </tr>
    <tr>
      <td>2</td>
      <td>Carbon</td>
      <td>~18%</td>
      <td>Backbone of organic compounds (proteins, fats, carbs, DNA)</td>
    </tr>
    <tr>
      <td>3</td>
      <td>Hydrogen</td>
      <td>~10%</td>
      <td>Water, most organic molecules</td>
    </tr>
    <tr>
      <td>4</td>
      <td>Nitrogen</td>
      <td>~3%</td>
      <td>Amino acids, proteins, DNA/RNA bases</td>
    </tr>
    <tr>
      <td>5</td>
      <td>Calcium</td>
      <td>~1–2%</td>
      <td>Bones/teeth, muscle contraction, signaling</td>
    </tr>
    <tr>
      <td>6</td>
      <td>Phosphorus</td>
      <td>~1%</td>
      <td>Bones/teeth, ATP, DNA/RNA</td>
    </tr>
    <tr>
      <td>7</td>
      <td>Potassium</td>
      <td>~0.2–0.3%</td>
      <td>Nerve impulses, heart rhythm, fluid balance</td>
    </tr>
    <tr>
      <td>8</td>
      <td>Sulfur</td>
      <td>~0.2%</td>
      <td>Protein structure, enzymes</td>
    </tr>
    <tr>
      <td>9</td>
      <td>Sodium</td>
      <td>~0.1–0.2%</td>
      <td>Extracellular fluid balance, nerve impulses</td>
    </tr>
    <tr>
      <td>10</td>
      <td>Chlorine (chloride)</td>
      <td>~0.1–0.2%</td>
      <td>Charge balance, stomach acid, pH regulation</td>
    </tr>
  </tbody>
</table>

Tiny Perspective Shift

If you looked by number of atoms instead of mass, hydrogen would jump much higher in rank, because hydrogen atoms are very light but extremely numerous.

But for everyday biology and nutrition, the mass‑based “top ten” list above is the one people usually mean.

Information gathered from public forums or data available on the internet and portrayed here.