Business, Legal & Accounting Glossary

Definition: Year-Over-Year


Quick Summary of Year-Over-Year

Year Over Year (YOY) refers to the mathematical process of comparing one year of data to the previous year of data.

Video Guide For Year-Over-Year

What is the dictionary definition of Year-Over-Year?

Dictionary Definition

In financial analysis and data analytics, YOY is the acronym for year over year.

yearoveryear calculation compares a statistic for one period to the same period the previous year. The period is typically based on a monthly or quarterly basis.

Year-over-year (YOY) is a term used frequently in investment research and other reports to mean “compared with the same period in the previous fiscal year.” Here’s an example: In a second-quarter earnings report for a company with a fiscal year-end of June 30, “Net income rose 12.2% year-over-year” means net income for the quarter ended December 31, 2X02, increased 12.2% from the net income reported in the quarter ended December 31, 2X01. Year-over-year is distinguished from quarter-over-quarter (or “sequential”) comparisons, where results are compared to those in the immediately preceding quarter. Most comparisons in investment reports are year-over-year because most businesses have at least some seasonal variation. For a department store chain where 80% of revenue is recorded in the Christmas quarter, only year-over-year comparisons make sense. But sequential comparisons may usefully accompany year-over-year comparisons — especially in the case of fast-expanding businesses where year-over-year comparisons don’t reflect the rapid rate of expansion. “Year-over-year” is usually unnecessary in full-year comparisons such as “Net income rose 12.2% in 2X02,” where a year-over-year comparison with results in full-year 2X01 can be assumed

Full Definition of Year-Over-Year

Year-Over-Year is a frequently used financial term and put simply it is where you compare the results from one year to another to identify annual trends, shifts in the market, or changes in performance amongst other things. A year-over-year (YOY) analysis is where you compare the results from one year with the results for the same period the year before. When completing a year-over-year analysis people will often look at the same month in each year, or the same quarter of each year.

The year-over-year growth rate determines the percentage change that has occurred throughout the last 12 months.

Looking at year-over-year performance allows you to see if a company’s financial performance is improving, staying stable, or worsening. For example, in financial reports, you may read that a specific company’s revenues increased on a year-over-year basis for the third quarter for the last three years.

Explanation of Year-Over-Year

A year-over-year comparison is an effective and popular way to evaluate both the performance of investments and the performance of a company. Any event that is both measurable and repeats annually can be evaluated using a year-on-year analysis. Often companies will use a year-on-year analysis to measure compare monthly, quarterly or annual performance.

Key Things To Remember

  • Year-over-year is an analysis tool to measure a minimum of two measurable events between one year and another year, usually between the present year with the previous year
  • Year-over-year evaluations are an effective tool for measuring the financial performance of a company, as a result, they are popular.
  • A year-over-year analysis will often be used by investors to determine a companies financial performance and so whether to invest.

Pros And Cons Of Year-Over-Year Analysis

Year-over-year (or year-on-year) comparisons are a popular and effective way to assess a company’s and investments’ financial performance. Any measurable event that occurs annually can be compared year over year. Annual, quarterly, and monthly performance are all common year-over-year comparisons.


  • A year-over-year analysis removes seasonality because it looks at specific points in time. For example, in the retail sector sales will rise in November and December due to Christmas. This shopping season accounts for almost 20% of annual sales for the sector, therefore it is the most critical time of the year. So it may be that you see a rise in sales, but that this happens every year. If you saw a 25% rise in sales for this period, you might be happy. However, if you compare it with the previous year and find that your sales rose 35% for this period you would realise that in fact, your sales are down for this period.
  • By using a year-over-year analysis you remove any market volatility from your data results, as you can now compare net results for the period being analysed
  • There is no need for a financial calculator or a spreadsheet as a year-on-year analysis is fairly easy to calculate
  • Results from a year-over-year analysis are displayed in percentages which makes it easy to compare companies of different sizes


  • If one time period had negative growth the results can be meaningless. If the company has experienced a time of negative growth, the following period of growth won’t make much sense.
  • A year-over-year analysis does not provide an in-depth analysis of a companies growth story, as a result, it should be used in conjunction with other business metrics. It provides a lot of information when used to compare just a few time periods, as it highlights trends, however it does not tell the whole story.
  • If problems have arisen in a given month, these may not show in a year-over-year analysis as it could just be comparing the whole year or quarter.
  • It will not provide you with the complete picture.

Something to remember: it is not considered a good idea to just rely on the year-over-year analysis of a companies financial position. It is useful to look at the monthly’s as well and be certain to use other metrics to give you a complete picture.

Examples of Year-Over-Year in a sentence

The £14.7 million figure expressed above represents 34.7% growth year-over-year.

This website had 75,000 page views on the third Friday of March, which was a 20% increase YOY.

Synonyms For Year-Over-Year


Cite Term

To help you cite our definitions in your bibliography, here is the proper citation layout for the three major formatting styles, with all of the relevant information filled in.

Page URL
Modern Language Association (MLA):
Year-Over-Year. Payroll & Accounting Heaven Ltd.
April 18, 2024
Chicago Manual of Style (CMS):
Year-Over-Year. Payroll & Accounting Heaven Ltd. (accessed: April 18, 2024).
American Psychological Association (APA):
Year-Over-Year. Retrieved April 18, 2024
, from website:

Definition Sources

Definitions for Year-Over-Year are sourced/syndicated and enhanced from:

  • A Dictionary of Economics (Oxford Quick Reference)
  • Oxford Dictionary Of Accounting
  • Oxford Dictionary Of Business & Management

This glossary post was last updated: 5th January, 2022 | 0 Views.