The “100 million” claim mainly traces back to Stéphane Courtois’s 1997 book The Black Book of Communism , where the number was used as a broad estimate of deaths attributed to communist regimes worldwide. It then spread through political speeches, activist material, memes, and retellings that often treat it as a precise fact rather than a contested estimate.

Where the number came from

Courtois and the book’s contributors tried to total deaths linked to communist states across several countries and decades, including executions, prison deaths, famines, labor camps, and other political violence. A key part of the math was adding very large estimates for the Soviet Union and China, especially deaths tied to famine and state repression.

The problem is that the figure is not a single measured count. It is a composite estimate built from highly debated categories, different time periods, and different methods for assigning responsibility. That is why critics say the number is useful as a political slogan but weak as a precise historical total.

Why it became a rumor

The number spread because it is simple, memorable, and morally charged. Once repeated in speeches, headlines, and online arguments, “100 million” became a shorthand for “communist regimes caused mass death,” even when the underlying methodology was not explained.

That simplification also blurred important distinctions:

  • deaths from deliberate political killing,
  • deaths from famine and policy failure,
  • deaths during wartime,
  • and deaths whose causes historians still debate.

What historians dispute

Historians disagree less about whether communist regimes caused immense suffering than about the exact totals and how to classify them. Some scholars argue the 100 million figure is plausible as an upper-range aggregate, while others say it overstates the case because it mixes different kinds of deaths and relies on uncertain estimates.

In short, the “100 million deaths from communism” line did not come from a single official census or universally accepted study. It comes from a late-1990s historical synthesis that later became a political talking point and then a viral slogan.

TL;DR

The claim comes mostly from The Black Book of Communism and was popularized as a broad estimate, not a precise body count. The number is widely repeated because it is memorable, but it remains contested because the method behind it bundles together different kinds of deaths and disputed assumptions.