The Swades Index is used to estimate when two languages diverged. If Language A and B share 86% of their core list, the index suggests they separated roughly 1,000 years ago.

This list is a cornerstone of and glottochronology —methods for quantifying language relatedness and potentially dating when languages diverged from a common ancestor. At its core, a Swadesh list is a curated set of around 100 to 200 core concepts—things like "I," "you," "water," "fire," "mother," and "bone"—that are thought to be universal and highly stable across all human languages.

No index is perfect. Critics of the Swades Index argue that it is a "protectionist's yardstick." The World Trade Organization (WTO) has expressed concern that governments might use a "low Swades Index" as justification for illegal subsidies or tariffs.