If you are interested in the economy, interest rates, stock prices, etc., you will want to get the Federal Reserve Bank of St. Louis Economic Data (FRED) Add-In. The FRED add-in provides free access to over 240,000 data series from various sources (e.g., BEA, BLS, Census, and OECD) directly through Microsoft Excel.
I created a spreadsheet that calculates inflation adjusted purchasing power using the consumer price index from the data I downloaded using FRED. You pick the starting year & month, a more current year & month and a dollar amount. The calculator gives the inflation adjusted purchasing power. As the new monthly CPI is released, you simply refresh the data with a click of the ribbon supplied with the FRED add-in, and you are up to date.
Download the spreadsheet “CPI“
Created in Excel 2013