How many languages have gone extinct in the last century?

How to get close to this number

Work from the rate. The explanation gives it as roughly one language every three months, and a century holds four hundred quarters. Rate times duration is the whole calculation, and converting between a rate and a total is the single most reusable technique across this entire site.

The projection is what makes the figure matter rather than merely being sad. Around three thousand more are classed as endangered, which means half of all human languages could be gone within a century at current rates. A historical count is only meaningful alongside a trajectory, and here the trajectory is the story.

Extinction is also harder to date than it sounds. A language does not stop on a particular day; it declines through a period when only elderly speakers remain, then a period when it is remembered but not used. Cataloguing bodies have to pick a criterion — usually the death of the last fluent speaker — and that choice makes the count a definitional exercise as much as an observational one.