This inflation calculator uses the consumer price index (CPI), which measures the average change in prices over time using a periodically updated market basket of goods and services. Through 1977, there was just one CPI measure. Starting in 1978, our calculator uses the CPI for all urban consumers (CPI-U).
The Minneapolis Fed maintains historical tables of inflation rates from 1913 to the present (when the modern methodology began) and estimated rates back to the year 1800 using various pre-1913 measures.
You can get the latest monthly data and learn more about different measures of inflation from the Bureau of Labor Statistics.