# Help explain this Inflation table to me **URL:** \ **Category:** Factual Questions\ **Created:** [January 26, 2011, 4:37am UTC](https://boards.straightdope.com/t/help-explain-this-inflation-table-to-me/569023 "2011-01-26T04:37:53Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![TNWPsycho](https://avatars.discourse-cdn.com/v4/letter/t/47e85d/32.png) [@TNWPsycho](https://boards.straightdope.com/u/TNWPsycho)\ **Post date:** [January 26, 2011, 4:37am UTC](https://boards.straightdope.com/t/help-explain-this-inflation-table-to-me/569023/1 "2011-01-26T04:37:53Z")
Im having a hard time understanding the monthly inflation chart at this website. [http://www.tradingeconomics.com/Economics/Inflation-CPI.aspx?Symbol=USD](http://www.tradingeconomics.com/Economics/Inflation-CPI.aspx?Symbol=USD) Did inflation seriously go up by 2.6% in Jan 2010? SO does that mean the overall inflation of 2010 was ~ 20%? WHat am i missing? ---
**Author:** ![Wendell\_Wagner](https://avatars.discourse-cdn.com/v4/letter/w/8491ac/32.png) [@Wendell\_Wagner](https://boards.straightdope.com/u/Wendell_Wagner)\ **Post date:** [January 26, 2011, 4:58am UTC](https://boards.straightdope.com/t/help-explain-this-inflation-table-to-me/569023/2 "2011-01-26T04:58:44Z")
It’s hard for me to tell, but I suspect what’s being given is the annualized rate of inflation. In other words, take the rate of inflation that happened during a month and pretend that that rate lasted for a year. That’s the annualized rate. The reason that this sort of rate is given is that it allows one to compare a recent month with some previous year. So if you’re told that the rate for the previous month was X percent and the rate for some year a while ago was Y percent, you want to know if the rate for the previous month was more or less than the rate for that year. The raw rate for that month doesn’t tell you that, since the raw rate for a month is almost certain to be less than the rate for a year. The annualized rate for the month allows you to compare the month with the year. ---
**Author:** ![Duckster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duckster/32/1244_2.png) [@Duckster](https://boards.straightdope.com/u/Duckster)\ **Post date:** [January 26, 2011, 5:50am UTC](https://boards.straightdope.com/t/help-explain-this-inflation-table-to-me/569023/3 "2011-01-26T05:50:41Z")
The key is in the December press release: > [@](#): > > The Consumer Price Index for All Urban Consumers (CPI-U) increased 0.5 percent in December on a seasonally adjusted basis, the U.S. Bureau of Labor Statistics reported on January 14. Over the last 12 months,the all items index increased 1.5 percent before seasonal adjustment. > > - snip - > > The rate of increase in the CPI slowed in 2010 as the December to December increase fell from 2.7 percent in 2009 to 1.5 percent in 2010. So it appears the monthly numbers are rolling annualized inflation rate numbers.