The Consumer Price Index (CPI) reflects the change in prices charged for consumer goods and services. It is often used as an indication of the inflation and/or the "cost of living." The CPI calculated monthly by the Bureau of Labor Statistics and announced on the 24th of the month following the month in question.
To find out exactly how the CPI is figured, see Labor Statistics Bureau Bulletin #2414 (BLS Handbook of Methods). Information is also posted on the BLS Web site (www.bls.gov/cpi/).
Current CPI Data: The most complete information for the U.S. is the Bureau of Labor Statistics' CPI Detailed Report. Information is also available on the Bureau of Labor Statistics' Inflation & Prices page. Or you can get right to current info by viewing the latest Federal reserve release; if you just want to see the annual rate of change (i.e., inflation), go right to Table 3, which provides data for All Urban Consumers (a) in the U.S., (b) by region and (c) for selected cities.
Other sources of CPI information: Moderately complete, and moderately current, are statistics published in BNA's Daily Report for Executives or Labor Relations Reporter/Labor Relations Expediter (LRX *).
Historical CPI Data: If you just want to a list of the overall CPI figures for prior years, the Federal Reserve Bank of Minneapolis posts the CPI from 1913-Present. For more complete historical final CPI data, use the BLS's CPI Databases. For unadjusted data (i.e., what the BLS originally announced), you can look at the appropriate back issue(s) of the CPI Detailed Report, available back to 1994 through the Archived News Releases page, and possibly farther back in print in larger public and academic libraries. To get the inflation rate for a date range (e.g., 1870-1885), use the "What was inflation then?" calculator on the How Much is That? web site.
You can also find historical CPI data in the American Jurisprudence 2nd Desk Book and Volume 1, Tab 10, "Economic Background for Bargaining," in BNA's Collective Bargaining: Negotiations and Contracts.
Inflation Calculators: To calculate the effect of inflation on the relative buying power of money (e.g., How much would $10 in 1950 be worth today?), use the What is a Dollar Worth? calculator on the home page of the Federal Reserve Bank of Minneapolis, the CPI Inflation Calculator posted by the Bureau of Labor Statistics, the U.S. Inflation Calculator or How Much is That?.
Foreign CPI Data: You can look up CPI data for foreign countries using Inflation Central by the Federal Reserve Bank of Cleveland. The IMF's International Financial Statistics includes cost of living data for many countries. In addition, CPI data for foreign countries is available on Lexis in one of the Bloomberg libraries. Also, the U.N. publishes foreign CPIs as Table 50 of its Monthly Bulletin of Statistics, though the data in the current issue is generally a few years old. How Much is That? has CPI data for British Pounds. The last page of each issue of The Economist has a financial data chart with the inflation rate for the major world economies.