How to Use Tom's Inflation Calculator
Two selectable data sets let you use Tom's Inflation Calculator for your own purposes. The default data is Consumer Price Index (Urban), 1665 to 2100. The alternative data set is the Social Security Wage Index, 1951 to 2012. Both let you 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. Use the Social Security data set when calculating wage inflation. For information about these data sets, scroll down this page to the section "Changing Data and Formatting Options."
Two Examples Using the Calculator
Example #1 (CPI-U inflation, backward in time): Suppose you just paid $3.50 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, $0.79appears below the Calculate button. So, after adjusting for inflation, a gallon of gasoline is indeed more expensive today (79 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 3.50 in the Dollar Amount field.
- Enter 2014 in the Starting Year field.
- Enter 1975 in the Target Year field.
- Click on the Calculate button.
Example #2 (wage inflation, forward in time): Let's say you were making $25,000 a year in 2000. Have your wages kept pace with general wage inflation since then?
The answerin this case, $34,457.12appears 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, 1951-2012.
- Enter 25,000 in the Dollar Amount field.
- Enter 2000 in the Starting Year field.
- Enter 2012 in the Target Year field. (Enter 2012, because the Social Security Administration will not release the 2013 data until after the federal fiscal year ends in September 2014.)
- Click the Calculate button.
Changing Data and Formatting Options
You can change data sets or switch dollar formatting on or off by clicking the appropriate buttons or the check box.
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 2014-2023) and my own forecasts for years beyond the CBO forecasts. (My annual forecast is 3.321 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 (Urban): 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.
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 2013, the program uses the inflation rates for 1991 to 2013.
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 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.
Inflation rates for 2014 through 2023 are the latest forecasts from the Congressional Budget Office, a nonpartisan source. Inflation rates for years beyond 2023 are my own guesstimates, based on the mean average inflation rate (3.321 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 an alternative data set.
For an interesting Italian inflation calculator with lots of features, see www.rivaluta.it
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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