How old is the Earth?
The Earth is about 4.54 billion years old, give or take 50 million years. Scientists know this from radiometric dating of meteorites and of the oldest rocks on Earth and the Moon.
Key facts
| Age | 4.54 ± 0.05 billion years |
|---|---|
| Method | Radiometric (uranium–lead) dating |
| Key measurement | Clair Patterson, 1956, Canyon Diablo meteorite |
| Oldest mineral | Zircon, 4.4 billion years (Australia) |
| Oldest rock | Acasta Gneiss, ~4.0 billion years (Canada) |
| Age of the Sun | ~4.6 billion years |
The Earth is about
4,540,000,000 years
old, and it gets one second older every second: 1.43 × 1017 seconds and counting.
How do we know the Earth's age?
By radiometric dating: some atoms, such as uranium, decay into others, such as lead, at a fixed rate. Measuring how much has decayed in a rock tells you how long ago it formed, like sand in an hourglass.
Earth's own surface keeps being recycled by plate tectonics, so its oldest rocks are younger than the planet. The best figure comes from meteorites, leftovers from the formation of the solar system. In 1956 the geochemist Clair Patterson measured lead in the Canyon Diablo meteorite and arrived at 4.55 billion years, a figure that has barely changed since.
The oldest things on Earth
| Oldest… | Age | Where |
|---|---|---|
| Mineral grains (zircon) | 4.4 billion years | Jack Hills, Western Australia |
| Rocks | about 4.0 billion years | Acasta Gneiss, Canada |
| Evidence of life | at least 3.5 billion years | Stromatolites, Western Australia |
| Moon rocks | about 4.5 billion years | Brought back by Apollo |
Earth's history on a 24-hour clock
If the Earth's 4.54 billion years were one day, the first life appears before 6 a.m., the first dinosaurs appear at about 10:47 p.m. and die out at 11:39 p.m., and modern humans appear in the last 6 seconds before midnight. Watch it play out on the Earth history clock.
What people used to think
In 1650 Archbishop James Ussher used Bible genealogies to date creation to 4004 BC. In the 1800s Lord Kelvin calculated from the Earth's cooling that it was 20 to 400 million years old; he didn't know about radioactivity, which keeps the Earth's interior hot. Radiometric dating in the 20th century settled it at about 4.5 billion years.
The universe is about three times older: see how old the universe is.
Questions people ask
How old is the Earth?
About 4.54 billion years (4.54 ± 0.05 billion), measured by radiometric dating of meteorites and the oldest Earth and Moon rocks.
How do scientists know the age of the Earth?
Radioactive elements decay at fixed rates. Measuring the uranium and lead in meteorites, which formed with the Earth, shows they are about 4.55 billion years old. Clair Patterson made the defining measurement in 1956.
What is the oldest rock on Earth?
The Acasta Gneiss in northern Canada, about 4.0 billion years old. Tiny zircon crystals from the Jack Hills in Western Australia are older still, about 4.4 billion years.
Is the Earth older than the Sun?
No. The Sun and the planets formed from the same cloud of gas and dust. The Sun is slightly older, about 4.6 billion years, and the Earth formed within a few tens of millions of years after it.
How much longer will the Earth last?
The Sun will make Earth too hot for oceans in about 1 billion years and will swell into a red giant in about 5 billion years. See when the world will end.
Last updated October 23, 2026.