How much iron there is

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

There is a great deal. Iron is about 5 to 6% of the Earth's crust. Known reserves hold about 87 billion tonnes of iron, some 54 years of mining at the 2025 rate. The limits are ore grade, carbon and mine safety, not the amount in the ground.

Last updated 3 October 2026.

In nature

How much of it there is, by mass, on a log scale

Universe 1,100 ppm ¹

Earth's crust 6.3% ¹

Seawater 3 ppb ¹

Human body 60 ppm ¹

Iron is the most common element on Earth by mass². Iron is the main element in the Earth’s core³. In the crust it is the fourth most common element, after oxygen, silicon and aluminum⁴. In one table of mass fractions, iron is 6.3% of the crust and 0.11% of the universe. In the same table, iron is 0.006% of the human body and 3 × 10⁻⁷ % of seawater¹⁵. Other estimates of the crust are lower: Geoscience Australia gives about 5%⁴.

The universe figure is high for a metal. Iron is the end point of fusion in the cores of massive stars. Fusing iron does not give a net yield of energy, so fusion stops and the star collapses⁶.

An adult body holds about 4 grams of iron in men and 3.5 grams in women. Most of it is in hemoglobin and myoglobin, the proteins that carry and store oxygen⁷. In geological terms iron is not rare. It is one of the main rock-forming elements⁴.

Reserves and resources

Reserves

87billion tonnes⁸

2025. Iron content of crude ore reserves (87 billion t; crude ore 200 billion t).

Australia's figure (27 billion t Fe) is larger than its JORC-compliant reserves (10 billion t Fe).

Resources

~ 260billion tonnes⁸

World resources of more than 260 billion t of iron, in more than 900 billion t of ore. USGS gives this as a lower bound.

The U.S. Geological Survey (USGS) gives world reserves of 200 billion tonnes of crude ore, which contain about 87 billion tonnes of iron⁸. USGS defines reserves as the part of known deposits that could be extracted at a profit when the estimate is made⁹. Resources are larger: more than 900 billion tonnes of ore with more than 260 billion tonnes of iron⁸.

Mines produced about 1.6 billion tonnes of iron in ore in 2025⁸. Reserves divided by production gives about 54 years (87,000 ÷ 1,600 million tonnes). This ratio is not a forecast of when iron runs out. It changes when prices and rules change. USGS lists Australia’s reserves at 27 billion tonnes of iron, but only 10 billion tonnes meet the Australian JORC reporting code or an equivalent⁸. Geoscience Australia ranks Australia’s economic resources of iron ore as the largest in the world. They were 30% of the world total at the end of 2024¹⁰.

Is it running out?

No. The crust is about 5 to 6.3% iron. The resources known today are more than 160 times the 2025 mine output (more than 260,000 ÷ 1,600 million tonnes)⁸⁴.

The real limits are ore grade, carbon and mine safety. Until recently most Australian deposits needed more than 60% iron to be worth mining; some ores of 56 to 59% are now mined⁴. Several Pilbara mines have built plants to upgrade low-grade ore before it is sold⁴. Most iron is made from ore with coal. The iron and steel sector emits about 2.6 billion tonnes of carbon dioxide a year¹¹. Tailings dams at Brazilian iron ore mines failed in 2015 and 2019¹².

About 30% of the metal fed to steelmaking worldwide is recycled scrap¹¹.

Sources

1
Theodore Gray (periodictable.com), data from Wolfram Research ElementData, 2026. Technical data for the element Iron , Abundances.

Abundance of iron in the universe, crust, oceans and humans, as mass fractions.
- % in Universe 0.11%
- % in Earth's Crust 6.3%
- % in Oceans 3 10 -7 %
- % in Humans 0.006%
- % in Universe … 0.11% … % in Earth’s Crust … 6.3% … % in Oceans … 3 10 -7 % … % in Humans … 0.006%
2
McDonough W.F. (Elsevier; copy on an Australian National University meeting page), 2003. Compositional Model for the Earth's Core (Treatise on Geochemistry, chapter 2.15) , Section 2.15.2, First-order geophysics.

Iron is the most abundant element in the Earth by mass.
- iron is the most abundant element, by mass
3
California Institute of Technology (Katie Neith), 2011. Ironing Out the Details of the Earth's Core .

Iron is the main element in the Earth's core.
- iron is the main element in the core
4
Geoscience Australia, 2023. Iron (Australian mineral facts) , Properties; Formation; Resources; Mining; Processing.

Ore minerals and their iron content, banded iron formations, Hamersley Province deposit types and grades, processing.
- It is the fourth most abundant element after oxygen, silicon and aluminium
- constituting about 5% of the Earth’s crust
- Iron (Fe) is one of the most abundant rock-forming elements
- until recently most deposits needed to have an average grade of more than 60% iron for mining to be commercially viable. However, some deposits can now have iron grades between 56%-59% iron
- ore processing facilities have been constructed to enable beneficiation of low-grade iron ores
5
Wolfram Research, 2026. ElementData , Details: 'Abundance properties include (specified by mass-fraction)'.

Wolfram states that the abundance values on periodictable.com are mass fractions.
- specified by mass-fraction
6
NASA Goddard Space Flight Center, 2009. Supernovae (Imagine the Universe!) , Supernovae from Single, Massive Stars.

Fusion in the core of a massive star stops at iron, because fusing iron gives no net energy.
- When the core contains essentially just iron, it has nothing left to fuse. (Because of iron’s nuclear structure, fusing iron does not result in a net yield of energy
7
Uwitonze A.M., Murererehe J., Rehman M., Chittilla M. and others (Frontiers in Nutrition), 2023. Oral manifestations of iron imbalance , Introduction; Iron metabolism.

Body iron of about 4.0 g in men and 3.5 g in women, and its share in hemoglobin and myoglobin.
- Body iron content is approximately 4.0 gm in men and 3.5 gm in women … The majority of iron (60–70%) is in the hemoglobin, 10% is in muscle myoglobin
8
U.S. Geological Survey (C.C. Tuck), 2026. Iron Ore, in Mineral Commodity Summaries 2026 , p. 2, World Mine Production and Reserves table; World Resources.

World mine production, reserves and resources of iron ore and its iron content, 2024 and 2025.
- Crude ore Iron content ... 200,000 ... 87,000
- World resources are estimated to be greater than 900 billion tons of iron ore containing more than 260 billion tons of iron
- Crude ore Iron content … 200,000 … 87,000
- Iron content … 2,600,000 2,600,000 1,600,000 1,600,000
- For Australia, Joint Ore Reserves Committee-compliant or equivalent reserves were 24 billion tons of crude ore and 10 billion tons of iron content
- containing more than 260 billion tons of iron
9
U.S. Geological Survey, 2026. Mineral Commodity Summaries 2026 .

Production, reserves, prices and end uses for about 90 mineral commodities, mostly for 2025.
- that part of the reserve base that could be economically extracted or produced at the time of determination
10
Geoscience Australia, 2025. World Rankings, in Australia's Identified Mineral Resources 2025 , Table 5, Iron Ore row (as at December 2024).

Australia ranks first for economic resources of iron ore (30% of the world) and first for production (38%) in 2024.
- iron ore, lead, rutile, uranium, vanadium, zinc and zircon were the world … Iron Ore … 30%
11
International Energy Agency, 2020. Iron and Steel Technology Roadmap: Towards more sustainable steelmaking , Executive summary.

Sector CO2 emissions (2.6 Gt, 7% of the energy system), coal use, scrap share and energy, demand projection to 2050.
- directly accounts for 2.6 gigatonnes of carbon dioxide
- iron ore is the source of around 70% of the metallic raw material inputs to steelmaking globally, the rest is supplied in the form of recycled steel scrap
12
Zhu F., Zhang W., Puzrin A.M. (Communications Earth & Environment), 2024. The slip surface mechanism of delayed failure of the Brumadinho tailings dam in 2019 , Abstract; Introduction.

Brumadinho dam failure on 25 January 2019, 270 deaths, and the link to the 2015 Fundão failure.
- The Brumadinho dam disaster occurred just three years after the failure of the Fundão dam