CPI Inflation Calculator — US Dollars, 1913–2024

How Inflation and Purchasing Power Conversion Work

Inflation is the sustained rise in the general price level over time — which means the purchasing power of money steadily falls. The same $100 that filled a grocery cart in 1990 buys far less today. The most widely used measure of inflation is the Consumer Price Index (CPI): statistical agencies track the prices of a fixed basket of everyday goods and services (food, housing, transportation, medical care and more), weight them by typical household spending, and combine them into a single index. The percentage change in that index is the inflation rate.

The conversion formula is straightforward: equivalent value = original amount × (target-year CPI ÷ starting-year CPI). For example, the US CPI annual average was 130.7 in 1990 and 314.2 in 2024, so $100 in 1990 is worth roughly $240 in 2024 — cumulative inflation of about 140%. Swap the years and you can also answer the reverse question: how much would today's money have been worth decades ago? That is handy for reading historical documents, comparing old movie ticket prices, or making sense of the salaries your grandparents mention.

The data comes from the US Bureau of Labor Statistics CPI-U (Consumer Price Index for All Urban Consumers), annual averages with a 1982–84 = 100 base period. The US series is the longest continuously published official inflation record in the world, running since 1913, and the dollar has long served as the international unit of account — which makes it the most useful common yardstick for comparing purchasing power across eras. Keep in mind that CPI reflects average price changes; your personal inflation rate depends on what you actually buy, and items like housing and tuition have often outpaced headline CPI. Use this tool as a starting point for understanding the time value of money when planning savings and investments.