How to Use Tom's Inflation Calculator
Six selectable data sets let you use Tom's Inflation Calculator for your own purposes. The default inflation data is the Consumer Price Index (Urban), 1665 to 2100. The other data sets cover fewer years. All of them can perform calculations forward or backward in time, for any years within their ranges.
For most purposes, the default data is sufficient. It's the U.S. government's Consumer Price Index for All Urban Consumers (CPI-U), Annual Average. Use this data set when calculating price inflation for goods and services or to see how wages are keeping up with those prices. For wage inflation, use the Social Security data set. For information about these data sets, scroll down this page to the section "Changing Data and Formatting Options."
See more instructions and examples below. For a question-and-answer format of basically the same information, see Tom's Inflation Calculator Frequently Asked Questions.
Two Examples Using the Calculator
Example #1 (CPI-U inflation, backward in time): Suppose you just paid $2.90 for a gallon of regular gasoline. Somebody tells you that gasoline cost only 50 cents a gallon in 1975. But was gasoline really cheaper back then, after allowing for inflation?
The answerin this case, $0.62appears below the Calculate button. So, after adjusting for inflation, the $2.90 gallon of gasoline is more expensive today (62 cents) than it was in 1975 (50 cents).
- To find out, make sure the default data set is selected: Consumer Price Index (Urban), 1665 to 2100. The data set is selected and indicated by the adjacent buttons.
- Enter 2.90 in the Dollar Amount field.
- Enter 2018 in the Starting Year field.
- Enter 1975 in the Target Year field.
- Click on the Calculate button.
Example #2 (wage inflation, forward in time): Suppose you were making $25,000 a year in 2000. Have your wages kept pace with general wage inflation since then?
The answerin this case, $39,121.88appears below the Calculate button. If your current salary is less, you haven't kept up with general wage inflation. Time for a raise!
- To find out, select the alternative data set, Social Security Wage Index, 1951-2017.
- Enter 25,000 in the Dollar Amount field.
- Enter 2000 in the Starting Year field.
- Enter 2017 in the Target Year field. (Enter 2017, because the Social Security Administration will not release the 2018 data until after the federal fiscal year ends in September 2019.)
- Click the Calculate button.
Changing Data and Formatting Options
You can turn dollar-and-cents formatting on or off using the check box. The default setting is on. Turning it off shows the raw answer. You can also select from five different sets of inflation data:
Far-future forecasts: Tom's Inflation Calculator can make inflation estimates as far forward as the year 2100 as part of the Consumer Price Index data set. These inflation rates are based on forecasts by the Congressional Budget Office (for the years 2018-2027) and my own forecasts for years beyond the CBO forecasts. (My annual forecast is 3.242 percentthe mean average inflation rate since the government began collecting these statistics in 1913.) These inflation estimates let you roughly estimate how much your retirement savings will be worth in future years. (My thanks to Penelope Reznor and Kodi Wolf for suggesting these extensions.)
- Consumer Price Index (CPI-U): This measure of inflation is often quoted in news stories and is the basis for cost-of-living adjustments (COLAs) by Social Security and many union contracts. It's the Consumer Price Index (CPI) for All Urban Consumers (CPI-U). It represents the annual average of monthly inflation rates in a calendar year for goods and services purchased by about 87 percent of the U.S. population. This is the default data set in Tom's Inflation Calculator.
- Social Security Wage Index: This is a wage-inflation data set compiled by the Social Security Administration since 1951. The SSA has extensive visibility into U.S. wages because of its automatic payroll-tax withholdings.
- Medical-Cost Inflation: This data set covers U.S. medical-cost inflation since 1935. It's actually part of the overall CPI-U. (My thanks to Sam Baker for suggesting this breakout.) Please note that this data set tracks the inflation of actual medical costs, not the inflation of health-insurance premiums, which generally rise faster than medical costs.
- CPI-U, December to December: This data set measures U.S. price inflation using the government's December-to-December data instead of the annual average data. The difference is subtle. The December-to-December data compares retail prices in December of a given year with retail prices exactly one year earlier. The annual average data is the mean average of inflation rates for all 12 months in a calendar year.
Over time, the difference between these two inflation rates rarely matters. However, my Inflation Calculator now includes the December-to-December data because some news stories refer to it, and occasionally, people ask why the inflation rates in my program seem to vary from those they heard about elsewhere. For example, in 2009, the annual average inflation rate was -0.4% (actually, deflation), whereas the December-to-December inflation rate was +2.7%.
The annual average rate is used more widely, so my program defaults to it. Note that the December-to-December data covers only the years 1913 to the most recent year for which government data is available. The annual average data in this calculator covers the years 1665 to 2100 by using historical data and forecasts.
- Personal Consumption Expenditures Price Index: This data set is less well known than the other government inflation indexes but probably has more effect on the U.S. economy, because it's the one the Federal Reserve uses to guide its monetary policy. For example, when you hear that the Fed's inflation-rate target is 2%, the PCEPI is the Fed's official yardsticknot the Consumer Price Index commonly quoted in news reports. Over time, the PCEPI tends to be lower than the CPI. That's important, because the Fed hesitates to raise its key interbank interest rate unless inflation meets or exceeds the target. Because of its importance, I added this data set to my program in February 2016 and revised it in March 2016 by substituting the "annual end-of-period percent change" data for the "annual average percent change" data. The PCEPI is compiled by the U.S. Bureau of Economic Analysis.
- ShadowStats (U.S. Price Inflation): This data set measures U.S. retail price inflation using statistics not compiled by the U.S. government. Instead, this data is provided with the permission of ShadowStats, a private company. (My thanks to ShadowStats author John Williams for his cooperation.)
ShadowStats data is an alternative to the official inflation data from the U.S. Bureau of Labor Statistics. In general, ShadowStats says that actual inflation is much higher than the government's official statistics. Although the ShadowStats inflation seems much higher than the inflation in my personal experience, some people want an alternative to the U.S. government data. ShadowStats data is proprietary and copyrighted. Although ShadowStats has granted me permission to use some of its data in my Inflation Calculator, my program is not permitted to display the data. For information about ShadowStats, see www.shadowstats.com.
Displaying Inflation Rates
You can see inflation rate percentages for all years in the currently selected data set by clicking the Show Inflation Data button. Note that this button is disabled (grayed out) until after performing an inflation calculation. If the Inflation Data window doesn't appear even after clicking the enabled button, your web browser may be blocking pop-up windows to discourage unwanted advertisements; please check your browser settings.
If the inflation percentage is a negative number, it indicates deflation for that year. The Inflation Data window also displays the data source and the cumulative inflation rate for the range of years selected. Note that the cumulative rate is derived iteratively, not merely by summing the inflation percentages for each year. The cumulative number shows the total amount of inflation during the years you selected. (Thanks to Cy Coleman for suggesting this feature.)
A Few More Hints
Note: The target year's inflation rate is the inflation since the previous year. For instance, if you calculate inflation from 2012 to 2013, the program uses the 2013 inflation rate. If you calculate inflation from 1990 to 2017, the program uses the inflation rates for 1991 to 2017.
This program uses only annual inflation data, not monthly data, so it has a worst-case error of 12 months and an average error of 6 months. In the worst case, it will overstate the actual inflation by 12 months if your starting date is December 31 and your target date is January 1. To the program, a year has passed, but a year's worth of inflation doesn't happen overnight.
This program uses inflation data from several sources, including Global Financial Data, Economic History Services, the U.S. Bureau of Labor Statistics, the Congressional Budget Office, and the Social Security Administration. The Personal Consumption Expenditures Price Index (PCEPI) is compiled by the U.S. Bureau of Economic Analysis and is available from the Federal Reserve Bank of St. Louis. This data is the annual-average percent change as measured from December to December, and (unlike the other inflation rates) is seasonally adjusted.
The most widely quoted inflation rate is the U.S. government's Consumer Price Index (CPI), 1913 to present, as compiled by the U.S. Bureau of Labor Statistics. By default, my Inflation Calculator uses the CPI-U (CPI All Urban Consumers) data, not seasonally adjusted (data series CUUR0000SA0). Data before 1913 was mostly reconstructed by economists from old records and is less reliable. The CPI-U includes medical-care inflation (data series CUUR0000SAM).
Inflation rates for 2018 through 2027 are the latest forecasts from the Congressional Budget Office, a nonpartisan source. Inflation rates for years beyond 2027 are based on the mean average inflation rate (3.242 percent per year) since the U.S. government began collecting these statistics in 1913.
If you want to learn more about how the U.S. Bureau of Labor Statistics gathers inflation data, the San Francisco Chronicle published an interesting article about a BLS "shopper." These professional shoppers spend their days canvassing stores, checking retail prices on the kinds of products American consumers are buying. The article was published on April 30, 2006, and is headlined, "A Measure of What's in Store". On February 24, 2008, the San Francisco Chronicle published an article discussing the shortcomings of the CPI: "Consumer Price Index a Real Guessing Game".
The U.S. Bureau of Labor Statistics has an inflation calculator. It uses the same CPI-U (annual average) data that my Inflation Calculator uses by default. However, answers may vary when converting values to the present year, because the BLS calculator includes the latest monthly inflation data. For my calculator, I update the CPI data only once a year (in January), when the data is more settled. (The government sometimes revises its monthly inflation data and makes seasonal adjustments.) When converting between other years, rounding errors during calculations may cause insignificant differences between the answers. Also, the BLS calculator covers only the years 1913 to present. Unlike my Inflation Calculator, it doesn't include historical data going back to 1665 or the forecasts to 2100. Nor does it have alternative data sets.
For an interesting Italian inflation calculator and website, see https://www.rivaluta.it/calcolatore-inflazione.asp
Penn State University has a Living Wage Calculator that accounts for differences in cost of living in various parts of the U.S. It's part of Penn State's Poverty in America Project.
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