Inflation is often called the **silent thief** because it slowly erodes your purchasing power over time without you noticing. At 3% average annual inflation, **$100 loses half its purchasing power in about 24 years. ** That $100 bill in your wallet today will buy roughly $50 worth of goods in 2049.
Understanding inflation is essential for saving, investing, and planning for retirement.
What Is the Consumer Price Index (CPI)?
The Consumer Price Index (CPI) measures the average price level of a fixed basket of goods and services purchased by urban consumers. it's the most widely used measure of inflation in the United States, published monthly by the Bureau of Labor Statistics.
The CPI basket includes food, housing, energy, transportation, medical care, education, and recreation — weighted by typical consumer spending patterns. The basket is periodically updated to reflect changing consumption (streaming services and smartphones are now included, for example).
| CPI Component | Typical Weight | Examples |
|---|---|---|
| Housing | ~33% | Rent, mortgage interest, utilities, furniture |
| Transportation | ~16% | New and used vehicles, gas, airfare, insurance |
| Food & Beverages | ~14% | Groceries, restaurant meals, alcohol |
| Medical Care | ~8% | Doctor visits, hospital services, prescriptions |
How Does the Inflation Formula Work?
The inflation adjustment formula is straightforward: **Adjusted Value = (Original Amount / CPI in Start Year) x CPI in End Year.** If prices in year B are 50% higher than in year A, then $100 in year A has the same purchasing power as $150 in year B.
The cumulative inflation rate tell you the total price change over a period. The average annual rate smooths that into a per-year percentage. Both are calculated directly from the CPI ratio between the two years.
This inflation calculator uses the same official CPI data from the Bureau of Labor Statistics that powers bls.gov. Annual average CPI values are used for each year. For month-to-month precision, the BLS provides monthly CPI data for calculations within a single year.
See How Inflation Affects Your Money
Enter any dollar amount and year range into our free Inflation Calculator. See the inflation-adjusted value, cumulative inflation rate, and annual average rate using official BLS CPI data from 1913 to today.