Year-over-year (YoY) is a comparison of a metric to the same period a year earlier, used to measure growth while controlling for seasonality.
Category
Metrics
Also known as
YoY; year on year
Comparing a metric to the same month last year, rather than to last month, helps remove seasonal swings that would otherwise distort the interpretation. It is a reporting default for revenue, AOV, and retention, and its main trap is comparing periods that are not truly comparable, such as a promotion last year against a quiet month this year.
In practice
Before trusting a YoY number, check that the two periods are actually alike. A clean YoY comparison controls for seasonality; a careless one can hide a one-off in either period and read it as a trend.
Discuss this term
A question, a bug, or outdated info? Tell us — it goes straight to the team, and we keep the glossary current.