---
title: "How many base pairs are in human DNA? about 3.1 billion per co"
description: "about 3.1 billion per copy — 6.2 billion in most cells How the figure is estimated, how confident it is, and what makes the scale graspable."
url: https://atoneplace.net/how-many/dna-base-pairs/
site: "At One Place"
---

# How many base pairs are in human DNA?

**How many base pairs are in human DNA?: about 3.1 billion per copy — 6.2 billion in most cells**

Stretched out, the DNA in one cell is about two metres long. Across 30 trillion cells that is roughly 60 billion kilometres — about ten times the distance to Pluto.

The human genome is about 3.1 billion base pairs long, and because most cells carry two copies — one from each parent — a typical nucleus holds around 6.2 billion. Only about 1.5% of it codes for protein, across roughly 20,000 genes, which is fewer genes than a water flea has. The genome was declared complete in 2003 but about 8% remained unread until 2022, when long-read sequencing finally resolved the repetitive centromeric regions.

## How the figure is arrived at

Sequencing: chop the genome into overlapping fragments, read each one, and reassemble by overlap. Short-read sequencing could not resolve long repeated stretches, which is why the last 8% waited two decades for reads long enough to span them.

## How confident it is

- **Low estimate:** 3,000,000,000
- **High estimate:** 3,200,000,000
- **Spread:** 1.1× between the bounds

## Other the human body counts

- [How many bones are in the human body?](https://atoneplace.net/how-many/bones-in-the-human-body/) — 206 in an adult — about 300 at birth
- [How many cells are in the human body?](https://atoneplace.net/how-many/cells-in-the-human-body/) — about 30 trillion human cells, plus 38 trillion bacteria
- [How many neurons are in the human brain?](https://atoneplace.net/how-many/neurons-in-the-brain/) — about 86 billion
- [How many muscles are in the human body?](https://atoneplace.net/how-many/muscles-in-the-human-body/) — about 600 skeletal muscles
- [How many hairs are on your head?](https://atoneplace.net/how-many/hairs-on-your-head/) — about 100,000
- [How many taste buds do you have?](https://atoneplace.net/how-many/taste-buds/) — about 2,000 to 8,000
- [How long are all your blood vessels?](https://atoneplace.net/how-many/blood-vessels-length/) — commonly quoted as 100,000 km — but probably closer to 20,000

## Common questions

### How many base pairs are in human DNA?

about 3.1 billion per copy — 6.2 billion in most cells

### How is that estimated?

Sequencing: chop the genome into overlapping fragments, read each one, and reassemble by overlap. Short-read sequencing could not resolve long repeated stretches, which is why the last 8% waited two decades for reads long enough to span them.

## Related pages

- [How many bones are in the human body?](https://atoneplace.net/how-many/bones-in-the-human-body/)
- [How many cells are in the human body?](https://atoneplace.net/how-many/cells-in-the-human-body/)
- [How many neurons are in the human brain?](https://atoneplace.net/how-many/neurons-in-the-brain/)
- [How many muscles are in the human body?](https://atoneplace.net/how-many/muscles-in-the-human-body/)
- [How many hairs are on your head?](https://atoneplace.net/how-many/hairs-on-your-head/)
- [How many taste buds do you have?](https://atoneplace.net/how-many/taste-buds/)
- [How long are all your blood vessels?](https://atoneplace.net/how-many/blood-vessels-length/)
- [How many people are there in the world?](https://atoneplace.net/how-many/people-alive-right-now/)
- [How many stars are there in the universe?](https://atoneplace.net/how-many/stars-in-the-universe/)
- [How many countries are there in the world?](https://atoneplace.net/how-many/countries/)
- [How many grains of sand are there on Earth?](https://atoneplace.net/how-many/grains-of-sand-on-earth/)
- [How many ants are there in the world?](https://atoneplace.net/how-many/ants-on-earth/)
- [How many trees are there in the world?](https://atoneplace.net/how-many/trees-on-earth/)

## Sources

- Typical range compiled from manufacturer specifications — At One Place (/about/)