# Year over year

> A comparison of a period with the same period a year earlier, to see growth after seasonality.

Source: https://sporetag.com/glossary/year-over-year
Also called: YoY, YoY growth, year on year.

YoY change = (this period − the same period last year) ÷ the same period last year × 100. From 1,200 orders last October to 1,380 this October is +15 percent. (Example numbers.)

It removes the seasonality a month-over-month comparison cannot: a store that compares December with November sees a boom every year, and a crash every January. For daily and weekly numbers, compare with the days 364 days back (52 weeks), so a Saturday lines up with a Saturday; for whole months and quarters, use the same dates.

A YoY change is only as good as the tracking behind both years: a new tag, a consent banner or a new bot filter can move the counts more than the business did. See [year over year comparison in analytics](https://sporetag.com/guides/year-over-year-comparison).

## Related terms

- https://sporetag.com/glossary/conversion-rate
- https://sporetag.com/glossary/session
- https://sporetag.com/glossary/pageview