How Many Gen Z Are There? The Ranking, and the Band-Width Problem
Gen Z is roughly 1.7 billion — third behind Gen Alpha and Millennials. But the bands cover different numbers of birth years, so the ranking partly measures width.
Generation Z numbers roughly 1.7 billion people worldwide across thirteen birth years, placing it behind Generation Alpha at about 2 billion and Millennials at about 1.8 billion — though part of that ordering reflects how many years each band covers.
Generation Z is roughly 1.7 billion people. That puts it third, and the ranking is more interesting than the number.
The comparison
| Generation | Birth years | Years in band | Approximate size |
|---|---|---|---|
| Generation Alpha | 2010–24 | 15 | ~2.01 billion |
| Millennials | 1981–96 | 16 | ~1.8 billion |
| Generation Z | 1997–2009 | 13 | ~1.7 billion |
| Generation X | 1965–80 | 16 | ~1.4 billion |
| Baby Boomers | 1946–64 | 19 | ~1.2 billion |
| Generation Beta | 2025–39 | 15 (1 so far) | ~137 million |
The band-width problem
Look at the third column before the fourth. Generation Z covers thirteen birth years. Millennials cover sixteen. Three extra years of births at roughly a hundred million a year accounts for most of the gap between them.
Adjusted for band width, Gen Z is not obviously smaller than the Millennials at all. The ranking is partly measuring a decision somebody made about where to draw lines.
This is worth knowing because "Gen Z is smaller than Millennials" gets used as an argument — about labour supply, about markets, about political weight — when a meaningful part of it is an artefact of the definition rather than a fact about the world.
Why Beta looks tiny and is not
Generation Beta shows as about 137 million against everyone else's billions. That is not a collapse in births — it is that the cohort opened on 1 January 2025 and has roughly one year of it so far.
It fills at about 132 million births a year and is projected to reach roughly 2.1 billion by 2039. Comparing a one-year-old cohort with a completed one is comparing a filling glass to a full one.
What size does and does not tell you
It does tell you the eventual ceiling on anything that scales with headcount — school places, entry-level jobs, eligible voters, addressable market for an age-bounded product.
It does not tell you current influence. A cohort's weight in any given year depends on what age it has reached, and that changes annually while the size does not. Generation Alpha is the largest cohort alive and its oldest members are sixteen; almost none of that two billion has entered the workforce, voted, or bought anything expensive.
For Gen Z the relevant fact is not the 1.7 billion. It is that the cohort is currently aged 17 to 29 — spread across school, university and early career simultaneously, which is when a single size figure tells you least.
See how every cohort compares at generation size statistics, or the projection behind Beta's figure at how big will Generation Beta be.