How Many Ants Are There on Earth?
About 2.4 Million per Person, and Together They Outweigh All Wild Birds and Mammals
Earth is estimated to hold about 20 quadrillion ants (a 2 followed by 16 zeros). The number is too big to picture, but a little arithmetic turns it into something familiar. It works out to more than 100 ants, on average, in every square metre of ground under your feet.
You are eating a rice ball on a park bench. A few grains fall, and before long a line of ants is marching to them. A moment ago, you could not see a single ant on the ground.
Where did they come from? They were there all along, just out of sight. Most ants live in the soil or under fallen leaves.
So how many ants are there on the whole planet? In 2022, a study pulled together surveys from around the world and answered that question with a number.
Two reasons there are so many
One ant weighs only a few milligrams. A single nest holds hundreds of ants, and in some species millions. A queen keeps laying eggs for years.
More than 14,000 named species are known. They live everywhere from tropical forests to deserts to the cracks in city pavements. Only a few very cold places, such as Antarctica, have none.
Tiny bodies, huge numbers, almost everywhere. Combine these and the total goes far beyond what we can imagine. Let's take it step by step.
How did anyone count them?
Nobody counted ants one by one. The researchers gathered 489 surveys done around the world. In those surveys, people set small pitfall traps in the ground or sifted fallen leaves, and counted the ants they found.
From these, the researchers worked out "how many ants per square metre" for each type of land, such as forest, grassland and desert. They multiplied each figure by the area of that type of land and added the results up. The answer was about 20 quadrillion ants.
Spread over all the land, that comes to about 130 ants per square metre on average. Try the slider in Figure 1 to change the area. A six-mat room (about 10 m²) holds over 1,000 ants, and a football pitch comes close to a million.
The figure of 20 quadrillion is considered a cautious one, covering mainly ants on the ground and in leaf litter. Ants that live high in trees or deep underground have not been counted well. The true number could be higher.
How much do they weigh all together?
Let's compare weight as well as number. The usual way to compare amounts of living things is by the weight of carbon in their bodies, because the amount of water varies with species and season.
All the ants together hold an estimated 12 million tonnes of carbon. Wild mammals hold about 7 million tonnes and wild birds about 2 million. So ants alone outweigh wild birds and wild mammals put together. See Figure 2.
Per ant, that is only about 0.6 milligrams of carbon. Yet 20 quadrillion of these tiny bodies add up to a fifth of the weight of all humanity.
What are all those ants doing?
With numbers this big, the ants' everyday work adds up to a force that shapes the whole of life on land. They dig nests and turn over the soil, opening paths for air and water. They carry off dead insects and handle the first step of decomposition.
They also carry plant seeds. Violet and dogtooth violet seeds come with a small "bonus" that ants like. The ants carry the seed to the nest, eat the bonus and throw the seed away. A violet blooming in a crack in the pavement may have grown from a seed an ant carried there.
E. O. Wilson and others, well known for their ant research, once estimated that the world has "1 to 10 quadrillion ants". That was a rough guess made by multiplying the number of insects overall by the share that are ants. The 2022 study instead added up counts from real surveys, and arrived at a higher figure of about 20 quadrillion.
Summary
Earth is estimated to hold about 20 quadrillion ants. That is about 2.4 million per person, or about 130 per square metre of ground on average. Each ant is tiny, but together they outweigh all wild birds and mammals combined. The ground under your feet is far busier than you might think.
One ant weighs less than a grain of rice.
But all of them together outweigh every wild bird and mammal.
To learn how ants form trails without getting lost, read "Why do ants form a neat line without losing their way?". For how these small creatures can be so strong, read "Why can ants lift loads dozens of times their own weight?". Turning huge numbers into familiar ones works the same way in "Does the air you just breathed contain air breathed out by people long ago?".
- On a sunny day in a park or garden, mark out a 50 cm square on the ground. Use string or twigs to mark the four corners.
- Put a small piece of biscuit in the middle and count how many ants gather in 10 minutes.
- Repeat in different places and compare, such as sun and shade, or bare soil and gaps in the paving.
The ants that come are only a small part of those in the nest. Imagine many times that number living below the surface. Don't touch ants with bare hands, so you won't get bitten or stung.
For those who want to know more: terms, formulas and links to textbooksEach part is labelled by level, from junior high science to university courses
- Junior highCovered in junior high school science
- High schoolCovered in high school biology (basic and standard courses)
- High school+Advanced high school material, or textbook sidebars
- UniversityNot taught in high school; university-level ecology and entomology
- ResearchNot yet settled even at university; questions researchers are studying now
Junior highTerms: this story has names
- Biomass: the amount of living things in a place, or on the whole Earth, expressed as weight. To make comparison easy, it is often given as the weight of carbon in their bodies.
- Social insects: insects that divide roles, as queens and workers do, and live in colonies. Ants, honeybees and termites are examples.
- Seed dispersal: when a plant has its seeds carried away from the parent. Dispersal by ants is called "myrmecochory".
Junior highHigh schoolChecking with a formula: how many underfoot, and how many per person?
Let's use the study's total to work out the average density and the number per person. The numbers are huge, so we write them as powers of 10 (10¹⁶ is a 1 followed by 16 zeros).
| In symbols | N ＝ ρ × A (average density ρ ＝ N ÷ A) |
| In words | Total ants ＝ ants per square metre × area of ground |
| Where it comes from | It is simply the definition of density. The study measured density for each type of land, such as forest, grassland and desert, multiplied by each area and added them up |
| N | Total number of ants |
| ρ | Ants per square metre (ants/m²) |
| A | Land area (m²) |
| Total ants (2022 estimate) | about 2×10¹⁶ ants (20 quadrillion) |
| Land area | about 1.5×10¹⁴ m² (150 million km²) |
| World population | about 8.2×10⁹ people (8.2 billion) |
| Carbon in all ants | about 1.2×10¹³ g (12 million tonnes) |
| Carbon in all humans | about 60 million tonnes |
| Average number per m², ρ | (2×10¹⁶) ÷ (1.5×10¹⁴) ≒ 133 ants |
| In a six-mat room (about 10 m²) | 133 × 10 ＝ 1330 ants |
| Per person | (2×10¹⁶) ÷ (8.2×10⁹) ≒ 2.4×10⁶ ants |
| Carbon per ant | (1.2×10¹³) ÷ (2×10¹⁶) ＝ 6×10⁻⁴ g |
| Weight compared with humans | 1200 ÷ 6000 ＝ 0.2 |
That is about 130 ants per square metre on average, or about 2.4 million per person. Each ant holds 0.6 milligrams of carbon. About half of a dried body is carbon, so the dry weight is around 1 milligram. Gather 20 quadrillion of them and they weigh a fifth as much as all humans.
High schoolHigh school+Where are they, and how many?
High schoolIn basic biology you learn to show the amount of living things in an ecosystem with a "biomass pyramid". Ants act as predators, plant-eaters and decomposers all at once, so they don't fit on a single level. They are the ecosystem's all-rounders.
High school+According to the 2022 study, ant numbers are highest in the tropics, especially in tropical forests and savannas. The same survey also reports that counts of ants walking on the ground came out higher than counts from within leaf litter.
UniversityEstimation methods, and the big picture of Earth's biomass
Two common ways to collect ants are the "pitfall trap", a container buried in the ground, and "Winkler extraction", where leaf litter is dried so the ants crawl out. The study grouped the densities from these methods by biome and extrapolated by multiplying by area. Linking it to the study that estimated Earth's biomass by taxonomic group (Bar-On et al., 2018) shows where the weight of ants fits.
📖 Derivations and further reading: Biomass — Wikipedia (Japanese) / Estimate of ant numbers and biomass (the original 2022 paper)
ResearchWhat is still not clear
- Ants in treetops and deep underground. Few surveys cover tropical treetops or deep soil, so we don't know how much they would add to the total.
- Poorly surveyed regions. Africa, Central Asia and other areas have few survey sites, so the estimate there has a wide margin.
- Are ants increasing or decreasing? Insect declines are reported in many places, but how ant numbers have changed over time is still unclear.
In other words, this article too is "an explanation of what is known so far". The figure of 20 quadrillion could move up or down with future surveys.
Links to textbooks (by level)
| Level | Subject / unit | Where in this article |
|---|---|---|
| Junior high | Science, Field 2: "Balance in nature", "decomposers" | Ants turning over soil and carrying off dead insects |
| High school | Basic biology: "Ecosystems", "biomass pyramid" | Figure 2, comparing weight by carbon |
| High school+ | Biology: "Animal behaviour", social insects | Reason 1: living in colonies means big numbers |
| University | Ecology and entomology (collection methods and extrapolated estimates) | How the ants were counted |
| Research | Estimating global biomass | Ants in treetops and underground, trends up or down |
| — | Links to daily life | Why ants find dropped food in the park so fast, violets in pavement cracks |
- Schultheiss, P. et al. (2022) The abundance, biomass, and distribution of ants on Earth. PNAS 119(40)
- Bar-On, Y. M., Phillips, R., Milo, R. (2018) The biomass distribution on Earth. PNAS 115(25)
- Hölldobler, B., Wilson, E. O. (1994) Journey to the Ants. Harvard University Press
- Terayama, M., Kubota, S., Eguchi, K. (2014) Encyclopedia of Japanese Ants (日本産アリ類図鑑). Asakura Shoten (朝倉書店)
Note: This article is a science explainer for general readers. The figures given are rough guides to help you understand how things work. The total number and weight of ants are research estimates and may change as surveys progress.