How many genes do humans have?

How many genes are in the human genome?

The human genome contains 78,691 genes in total, according to the latest GENCODE release (version 49, May 2025). This number includes not just the genes that code for proteins, but also a vast array of regulatory and non-coding genes that control how our bodies function.

For decades, scientists estimated the number of human genes to be as high as 100,000. It wasn't until the completion of the Human Genome Project that we realized our biological complexity does not come from a massive gene count—in fact, we have fewer genes than a water flea or an onion.

How many protein-coding genes do humans have?

Humans have approximately 19,433 protein-coding genes. This specific count refers to the genes that are transcribed into mRNA and then translated into proteins—the molecular machines that do most of the work in our cells.

While 19,000 might seem low for a complex organism, humans achieve complexity through alternative splicing. A single gene can be spliced in different ways to produce multiple protein variants (isoforms). As detailed in our protein count guide, these ~19,000 genes can generate over 70,000 distinct protein isoforms, vastly expanding the functional repertoire of our genome.

One major update to these numbers came from the Telomere-to-Telomere (T2T) consortium. In 2022, they published the first complete, gapless human genome (T2T-CHM13), revealing nearly 2,000 new gene predictions in regions that were previously unsequenced, including 99 potential protein-coding genes.

How many chromosomes do humans have?

Humans typically have 46 chromosomes in every nucleated cell, arranged in 23 pairs. We inherit one set of 23 chromosomes from our mother and one set of 23 from our father.

This set comprises:

• 22 pairs of autosomes (numbered 1–22 by size)
• 1 pair of sex chromosomes (XX for females, XY for males)

The total length of DNA across these 46 chromosomes is approximately 3.2 billion base pairs. Despite our complexity, other primates have slightly more chromosomes; great apes like orangutans, gorillas, and chimpanzees have 48 chromosomes (24 pairs).

[!NOTE] A common question is whether autism affects chromosome count. Autism Spectrum Disorder (ASD) is generally not caused by a change in chromosome number. Most people with autism have the typical 46 chromosomes. While some rare genetic conditions (like Down syndrome or Fragile X) involve chromosomal abnormalities and can co-occur with autistic traits, autism itself is complex and polygenic, not defined by a single chromosomal count difference.

How does the human gene count compare to other species?

Human "biological superiority" is not reflected in our gene count, a phenomenon known as the C-value paradox. Many simple organisms have more genes or larger genomes than we do.

This comparison highlights that complexity arises not from the sheer number of parts (genes), but from how those parts are regulated and combined.

Matic Broz

Founder & CEO, ProteinIQ

Matic founded ProteinIQ to make computational biology accessible to every researcher. He builds code-free bioinformatics tools used by thousands of scientists worldwide for protein analysis, molecular docking, and drug discovery.