How heavy is the Earth? About 5.97 × 10²⁴ kg, and how we know

Nobody has put the planet on a scale: the 5.9722 × 10²⁴ kg figure comes from dividing a very precisely measured orbital quantity, GM, by the gravitational constant G, which is known to only about five digits.

The Earth has a mass of about 5.972 × 10²⁴ kg, or 5.9722 × 10²⁴ kg in NASA’s Earth Fact Sheet. In US units that is roughly 1.32 × 10²⁵ pounds (about 13.2 septillion), or about 5.97 × 10²¹ metric tonnes. Scientists did not weigh it. They calculated it from how fast things fall around it.

The method is short: measure how strongly Earth pulls on satellites (a number called GM), measure the gravitational constant G in a laboratory, and divide. The first number is known to many digits. The second is not, so the uncertainty in Earth’s mass is almost entirely the uncertainty in G.

Explain it like I’m busy:

• Earth’s mass is about 5.972 × 10²⁴ kg: calculated as GM ÷ G, not weighed.
• Earth is about 81 Moons, but only 1/317.8 of Jupiter and 1/332,900 of the Sun.
• “Weight” is a force that depends on where you stand. Mass is how much matter there is. Earth has a mass, not a weight.

Key facts about Earth’s mass

• Value: 5.9722 × 10²⁴ kg (NASA Earth Fact Sheet, updated 15 November 2024). NASA’s planet table rounds this to 5.97 × 10²⁴ kg.
• Method: calculated. Mass = GM ÷ G, where GM is the product of G and mass, found by tracking orbits.
• The weak link: G, at 6.67430 × 10⁻¹¹ m³ kg⁻¹ s⁻² with a relative standard uncertainty of 2.2 × 10⁻⁵ (CODATA 2022, NIST).
• Cross-check: the mean density, mass divided by volume, comes out at about 5,513 kg/m³, matching NASA’s printed 5,513 kg/m³.
• Surface gravity: 9.820 m/s² (NASA mean value), which follows from the same GM and Earth’s 6,371 km volumetric mean radius.

Earth’s mass compared with the Moon, Sun and other planets

Source: NASA Space Science Data Coordinated Archive, Planetary Fact Sheets (Earth, Moon and Sun fact sheets; planet table and ratio table). Masses are NASA’s rounded values; the Moon’s comes from the Moon Fact Sheet and Earth’s from the Earth Fact Sheet. Ratios are NASA’s, except the Moon’s “1/81”, which is SciQuest’s calculation (5.9722 ÷ 0.07346 = 81.3).

What 5.97 × 10²⁴ kg means

The number is too large to feel, so use the ratio. Put 81 Moons together and you have about one Earth. Put 317.8 Earths together and you have one Jupiter. The Sun outweighs Earth by a factor of about 332,900, which means Earth holds roughly 0.0003% of the Sun’s mass (1 ÷ 332,900, our calculation).

A plain way to picture it: Earth is a very dense ball. Its mean density of 5,513 kg/m³ is about 5.5 times that of water, so the planet is far more than a ball of rock near the surface. The dense iron-rich core pulls the average up. (We unpack the layers in our guide to the layers of Earth.) The comparison has one limit: density is an average, and no single layer has that value.

How scientists know: mass = GM ÷ G

Newton’s law of gravitation says the pull between two masses depends on the product of the masses, a constant G, and the distance between them. For a small object orbiting Earth, the pull depends on G times Earth’s mass. Orbits reveal that product directly, because it sets how fast the object must move at a given distance. The product is written GM.

JPL’s Solar System Dynamics page lists GM for Earth as 398,600.435507 km³/s², taken from the DE440 ephemeris (Park et al., 2021, Astronomical Journal). It prints twelve significant figures. What orbits cannot do is separate G from M, because only their product shows up in the motion.

That separation needs a laboratory measurement of G, and the first one was Henry Cavendish’s in 1797 and 1798. He used a torsion balance, a rod hanging from a thin wire with small lead balls on each end, and measured how much large lead balls nearby twisted it. The design came from John Michell. Cavendish reported Earth’s density as 5.448 ± 0.033 times that of water (as summarised by Wikipedia; we did not open the 1798 paper itself).

Worked calculation, step by step

1. Convert GM to SI units: 398,600.435507 km³/s² × 10⁹ m³/km³ = 3.98600435507 × 10¹⁴ m³/s².
2. Take G = 6.67430 × 10⁻¹¹ m³ kg⁻¹ s⁻² (CODATA 2022).
3. Divide: M = (3.98600435507 × 10¹⁴ m³/s²) ÷ (6.67430 × 10⁻¹¹ m³ kg⁻¹ s⁻²) = 5.9722 × 10²⁴ kg (5.97217 × 10²⁴ kg before rounding).
4. Check the density: Earth’s volume is 1.08321 × 10¹² km³ (NASA), or 1.08321 × 10²¹ m³. Then 5.9722 × 10²⁴ kg ÷ 1.08321 × 10²¹ m³ = 5,513 kg/m³, the same as NASA’s mean density.

All four steps are SciQuest calculations from the cited inputs. JPL’s page cites the 2018 CODATA value of G, which is numerically the same as the 2022 value.

Where the uncertainty comes from

G’s relative standard uncertainty of 2.2 × 10⁻⁵ passes straight into the mass. Multiply 5.9722 × 10²⁴ kg by 2.2 × 10⁻⁵ and you get about 1.3 × 10²⁰ kg. That is about 1/560 of the Moon’s mass, so the answer is good to about five significant figures and no better, even though GM is known far more tightly. This is a calculation that treats GM as exact, so it understates the full uncertainty a little.

What changes the answer

Different sources print 5.97, 5.9722 and 5.972 × 10²⁴ kg. They agree. NASA’s planet table rounds to three significant figures, and its Earth Fact Sheet gives five. Quote the digits that match your use, and say which. Some older references still print 5.9736 × 10²⁴ kg, which is about 0.02% higher than NASA’s current figure.

The bigger issue is how well G is known. Two torsion-pendulum experiments reported in Nature in 2018 (Li and colleagues) found 6.674184 × 10⁻¹¹ and 6.674484 × 10⁻¹¹ m³ kg⁻¹ s⁻², using two different methods. The two differ from each other by about 45 parts per million, roughly twice the 22 parts per million that CODATA gives for G as a whole. The authors state that both values agree with the recommended value within two standard deviations. These two results differ in the fifth significant figure, and the sources we read do not settle why measurements of G spread that way.

Ratios have an advantage. The Earth-to-Moon mass ratio uses GM for both, so G cancels. JPL’s GM values give 398,600.435507 ÷ 4,902.800118 = 81.3006 (our calculation), a ratio known far more tightly than either mass alone.

Mass versus weight

Mass is the amount of matter and is measured in kilograms. Weight is the force gravity exerts on that mass, measured in newtons, and it changes with location. A 70 kg person weighs about 687 N at Earth’s surface, from 70 kg × 9.820 m/s². On Mars the same person has the same mass and a much smaller weight, a difference we work through in gravity on other planets and gravity on Mars.

Earth has no weight in this sense, because weight needs a second body pulling on it. When people ask “how heavy is the Earth,” the correct quantity is its mass, which is the same wherever you measure it from.

Why it matters to you

You won’t use this number in daily life, but you do use what it implies. Earth’s mass, with its radius, sets the 9.82 m/s² that decides how fast things fall, how high a jump goes, and how much fuel a rocket needs. The Moon’s smaller mass explains why gravity there is weaker; see how strong gravity is on the Moon.

“But wait…” if G is so uncertain, how do we trust GM?

GM comes from orbits, not from G, so G’s uncertainty never touches it. Satellites and spacecraft move according to GM alone. Orbital calculations can therefore use GM at full precision while the mass in kilograms stays uncertain at the fifth digit. The kilogram value is a conversion, and only the conversion carries G’s uncertainty.

Related questions

• How many Earths fit in the Sun? By mass, about 332,900 Earths. By volume, about 1.3 million. See how many Earths would fit in the Sun.
• How much more massive is Jupiter? 317.8 times Earth’s mass, per NASA. Its gravity is only about 2.4 to 2.7 times Earth’s at the cloud tops, because the radius is larger; see gravity on Jupiter.
• Is Earth’s mass changing? This article does not cover that, because we did not verify a source on mass gained from space dust or lost from the upper atmosphere.
• What is Earth’s density? 5,513 kg/m³ on average, per NASA.

In one sentence

Earth’s mass is about 5.9722 × 10²⁴ kg, found by dividing the orbit-derived product GM by the lab-measured constant G, which means the quality of the number rests on G.

Read next

• Gravity on other planets: what you would weigh on each world
• How many Earths would fit in the Sun? Earth size compared to Sun
• From crust to core: a detailed look at the layers of Earth

Sources

1. NASA NSSDC, Earth Fact Sheet (mass 5.9722 × 10²⁴ kg, volume, mean density 5,513 kg/m³, gravity 9.820 m/s², volumetric mean radius 6,371 km; updated 15 November 2024).
2. NASA NSSDC, Planetary Fact Sheet, metric and ratio to Earth (planet masses and mass ratios).
3. NASA NSSDC, Moon Fact Sheet (0.07346 × 10²⁴ kg) and Sun Fact Sheet (1,988,400 × 10²⁴ kg; ratio 332,900).
4. NASA/JPL Solar System Dynamics, Astrodynamic Parameters (GM for Earth, Moon, Sun; DE440, Park et al. 2021, Astronomical Journal 161:105).
5. NIST, CODATA 2022 value of the Newtonian constant of gravitation (6.67430(15) × 10⁻¹¹ m³ kg⁻¹ s⁻²; relative uncertainty 2.2 × 10⁻⁵).
6. Q. Li et al. (2018), Measurements of the gravitational constant using two independent methods, Nature 560, 582 to 588 (values read from the Europe PMC abstract record; journal full text not accessed).
7. Wikipedia, Cavendish experiment (1797 to 1798 torsion balance, John Michell, 5.448 ± 0.033 density result). This is a secondary source; we did not open Cavendish’s 1798 paper in Philosophical Transactions.

Disclosure: This article was drafted with AI assistance and checked against the sources above. Calculations by SciQuest: unit conversions, the GM ÷ G division, the density check, the 81.3 and 0.0003% ratios, the 687 N weight, the 1/560-of-a-Moon comparison and the ±1.3 × 10²⁰ kg uncertainty (which assumes GM is exact) are our own arithmetic from the cited inputs. The graphic is a SciQuest original. No outside expert was interviewed. Spotted an error? See our corrections policy.