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How much hydrogen there is

How much of it exists, and how much of that can we reach?

Hydrogen is the most common element in the universe and is part of every water molecule on Earth. Free hydrogen gas is rare. Industry makes what it needs from natural gas, coal or water, so there are no reserves in the usual sense.

Last updated 3 October 2026.

In nature

How much of it there is, by mass, on a log scale
Universe 74% 1
Earth's crust 450 ppm 2
Air 530 ppb by volume 3
Human body 10% 4

Hydrogen is the most abundant element in the universe5. It makes up about 74% of the mass of the Sun’s surface layer1. We use the Sun as a stand-in for the universe.

Estimates for the continental crust differ by a factor of three. Wedepohl (1995) gives 0.045% by weight, or 450 parts per million2. An older estimate by Mason (1966) gives 1,400 parts per million6, and the authors of a biology textbook give 0.1%4. Almost all of this hydrogen is in water and in hydrous minerals.

Free hydrogen gas (H2) is rare at the surface. Air holds about 530 parts per billion of it on average3. In most studies, soils remove 65% to 85% of the hydrogen that leaves the air. The hydroxyl radical (OH) in the air removes the rest3. A molecule stays in the air for about 2.4 years3.

The human body is about 10% hydrogen by mass4. It is in water and in almost every molecule of life5.

Reserves and resources

Hydrogen has no reserves in the sense that a metal ore has. Industry makes it from compounds that contain it, mostly natural gas and coal7. Water is the other raw material, through electrolysis5.

Natural hydrogen, also called geological hydrogen, forms underground. The main process is serpentinisation, a reaction between water and iron-rich rock7. In a 2024 model, two U.S. Geological Survey scientists give a very wide range for the hydrogen held underground. Their most probable value is about 5.6 trillion tonnes8. The authors state that most of it is likely impractical to recover8.

The IEA notes that no single well has a resource estimate, and that the potential must be proven by drilling7. These are model results, not reserves, so we give no reserves figure.

Is it running out?

No. The hydrogen atom is not scarce. Water alone holds far more hydrogen than industry could use. The limit is energy and cost. It takes energy to pull hydrogen out of water or methane, and the cheapest routes use fossil fuels.

Two international agencies agree that fossil fuels supply almost all hydrogen today. The IEA counts almost 1 million tonnes of low-emission hydrogen in 2025, out of about 103 million tonnes7. The International Renewable Energy Agency (IRENA) states that almost all hydrogen comes from fossil fuels9. In the United States, about 99% of hydrogen comes from fossil fuels10.

So the supply of hydrogen depends on the supply of natural gas and coal. In 2026 the war in the Middle East cut trade in ammonia, urea and sulfur through the Strait of Hormuz7. The real constraints are not geological. They are the price of gas, the cost of clean power and electrolysers, and the carbon dioxide released.

Sources

  1. 1

    Martin Asplund, Nicolas Grevesse, A. Jacques Sauval and Pat Scott, Annual Review of Astronomy and Astrophysics 47, 2009. The chemical composition of the Sun , Section 3.12, p. 24.

    Mass fraction of hydrogen in the Sun.

    • the mass fractions of H, He and metals in the present-day photosphere become X = 0.7381
  2. 2

    Laura Schaefer, Katharina Lodders and Bruce Fegley Jr., Astrophysical Journal, 2012. Vaporization of the Earth: application to exoplanet atmospheres , Section 3.2.1; Table 1 (continental crust, from Wedepohl 1995).

    Hydrogen in the continental crust by weight, and a comparison with other estimates.

    • We use 0.045 wt. % H as the hydrogen abundance in Earth's continental crust (Table 1) from Wedepohl (1995)
    • We use 0.045 wt. % H as the hydrogen abundance in Earth’s continental crust (Table 1) from Wedepohl (1995)
  3. 3

    Maria Sand and others, Communications Earth & Environment, 2023. A multi-model assessment of the Global Warming Potential of hydrogen , Abstract; Introduction; Results (hydrogen budget), Fig. 1.

    Hydrogen in the air, its sinks and lifetime, and its indirect warming effect.

    • Present-day hydrogen average abundances (mole fraction) are about 530 ppbv
    • Hydrogen is removed from the atmosphere by biological uptake in soils and atmospheric oxidation by the hydroxyl radical (OH) … accounts for 65-85% of the total hydrogen sink
    • the total lifetime of hydrogen is 2.4 years
  4. 4

    OpenStax, Rice University, 2018. Biology 2e, 2.1 Atoms, Isotopes, Ions, and Molecules: The Building Blocks , Table 2.1.

    Hydrogen is about 10% of the human body by mass.

    • Hydrogen (H) 10% trace 0.1%
    • Hydrogen (H) 10%
  5. 5

    Royal Society of Chemistry, 2026. Hydrogen: element information, properties and uses .

    History, uses and biological role.

    • Hydrogen is easily the most abundant element in the universe
    • It is present in water and in almost all the molecules in living things
    • Hydrogen can also be produced by the electrolysis of water
  6. 6

    Randy L. Korotev, Washington University in St. Louis, 2026. Terrestrial abundances of the elements .

    Bulk continental crust by mass from four compilations; hydrogen 1,400 ppm from Mason (1966).

    • bulk continental crust … H 1400
  7. 7

    International Energy Agency, 2026. Global Hydrogen Review 2026 , Executive summary pp. 9-14; Middle East effects p. 21; Box 1.1 p. 20; targets p. 31; geological hydrogen pp. 36-42; demand pp. 44-57; transport p. 62; production pp. 83-85, 106; costs pp. 110-116; RED transposition p. 133; trade p. 143; policy p. 194; definitions pp. 257-258.

    Hydrogen demand, production routes, costs, emissions, trade and natural hydrogen for 2025.

    • Global hydrogen production remains overwhelmingly based on unabated fossil fuels, mostly natural gas
    • serpentinisation is considered the most significant: reactions between water and iron-rich rocks that generate hydrogen
    • potential estimates are not available for any single well … needs to be physically validated through drilling
    • Low-emissions hydrogen production grew by 20% in 2025 to reach almost 1 Mt … 103 Mt H2
    • The closure of the Strait of Hormuz has constrained trade flows for ammonia, urea and sulphur
  8. 8

    Geoffrey S. Ellis and Sarah E. Gelman (U.S. Geological Survey), Science Advances, 2024. Model predictions of global geologic hydrogen resources , Abstract; Results, Fig. 3.

    Model estimate of natural hydrogen in place in the Earth's subsurface.

    • a wide range of values for the potential in-place hydrogen resource … with the most probable value of ~5.6 × 10
    • most of this hydrogen is likely to be impractical to recover
  9. 9

    International Renewable Energy Agency and World Trade Organization, 2024. Enabling global trade in renewable hydrogen and derivative commodities , Introduction; Market overviews (hydrogen, ammonia).

    World hydrogen production of about 95 Mt a year and emissions of about 1.3 Gt CO2-eq.

    • almost all hydrogen is produced from fossil fuels
  10. 10

    Congressional Research Service, 2024. Hydrogen Production: Overview and Issues for Congress (R48196) , Summary; pp. 2-4 and Figure 1; pp. 14-18.

    World production estimates and route shares from US DOE; the 45V tax credit, the hydrogen hubs and the debate in Congress.

    • approximately 99% of the 10 MMT of hydrogen produced annually in the United States is sourced from fossil fuels