Year over Year (YoY)
Definition
The year-over-year comparison relates a metric to the same period of the previous year.
The comparison of a metric with the same period of the previous year, absolute or percentage.
Simply explained
For example, you compare this October's sales with the sales from October of last year.
Why it matters in practice
The term is relevant for systematically improving digital visibility, qualified traffic, and content findability.
Example from business
A retailer compares sales October 2026 with October 2025 and separately reports price and volume effects.
Limits and pitfalls
- Calendar effects, acquisitions, definitions, and base effects can distort the comparison.
Origin & history
YoY comparisons are an established reporting form to reduce seasonal distortion.
Use in mid-sized companies
- Possible application: A retailer compares sales October 2026 with October 2025 and separately reports price and volume effects.
Frequently asked questions
What does year-over-year comparison (YoY) mean?
The comparison of a metric with the same period of the previous year, absolute or percentage. What should you watch out for? Calendar effects, acquisitions, definitions, and base effects can distort the comparison.
Sources
- calculating percent changes · U.S. Bureau of Labor Statistics, calculating percent changes
Source checked on 10.10.2026. Editorial usage examples are hypothetical; no proof of real customer results.
Editorially reviewed on: