What money from one year buys in another
When prices rise, the same dollars buy less. This uses the official U.S. price figures to show what an amount from one month is worth in another, and whether a pay rise kept up.
Did my pay keep up?
My pay went from one amount to another between the two dates above. Did my buying power go up or down?
How this is worked out: amount in end month = amount × (price index in end month ÷ price index in start month). Change in prices = (end index ÷ start index − 1) × 100%. For pay: pay needed to keep up = starting pay × (end index ÷ start index), and change in buying power = (current pay ÷ pay needed to keep up − 1) × 100%.
The price index is the Consumer Price Index for All Urban Consumers (CPI-U): the average price of a fixed basket of goods and services bought by people in U.S. cities, compared with 1982–84 (= 100). It is not seasonally adjusted, so it compares the actual prices in each month.
It is a national average. Your own costs depend on where you live and what you buy, so your personal inflation can be higher or lower. Pay is compared before tax. Only published monthly figures are used; when BLS did not publish a month, the calculator says so instead of guessing.
Source: U.S. Bureau of Labor Statistics, CPI-U, All items, U.S. city average, not seasonally adjusted, series CUUR0000SA0.