What this inflation calculator does
The inflation calculator converts a dollar amount from one year to another using the official US Consumer Price Index. It answers the everyday question: "$100 in 2000 was worth how much in today's money?" or the planning question: "If inflation runs 3% a year, what will $50,000 buy in 25 years?" Switch between the historical CPI mode (anchored in BLS data from 1913 to 2025) and a custom-rate mode for forward projections or alternate scenarios.
The math
CPI mode uses the standard ratio formula:
Adjusted = Original × (CPIend ÷ CPIstart)
The Annualised rate of inflation between the two years is shown next to the result — it's the geometric mean: (CPIend ÷ CPIstart)1/n − 1, where n is the number of years.
Custom-rate mode uses compound growth: Adjusted = Original × (1 + rate/100)years.
About the CPI data
The calculator uses CPI-U (Consumer Price Index for All Urban Consumers), base period 1982-84 = 100. It's published monthly by the US Bureau of Labor Statistics and is the headline inflation number you hear quoted on the news. Annual averages are used here (not single-month figures), and the data covers 1913 through 2025. The CPI-U number for a given year captures everything that happened during that year on average — wars, oil shocks, recessions, the Fed's response, supply chain disruptions, all of it baked into one number.
What CPI does and doesn't capture
CPI measures the average price change for a representative basket of urban-consumer goods and services. Big-picture, it captures groceries, rent, gas, utilities, healthcare, transport, entertainment and a long list of other categories. What it doesn't capture is your specific basket — if you spend most of your money on rent in San Francisco, real-estate-driven housing inflation can run very differently from headline CPI. Sub-indexes like CPI-Rent or CPI-Medical Care exist for that; this tool sticks to the headline number for general purchasing-power comparisons.
Why "real" returns matter
A 7% nominal investment return when inflation is 3% gives a real return of about 3.9% (not 4% — the math compounds). For long-term planning, real returns are what matter, because they tell you how much actual buying power you've gained. Use this calculator to convert a future projection (from the investment calculator or retirement calculator) back into today's dollars and see what your nest egg will really feel like.
Practical comparisons that surprise people
- A 1970 dollar buys what about $8 buys today — prices have multiplied roughly 8×.
- A 1990 dollar buys about $2.40 today.
- A 2000 dollar buys about $1.87 today.
- Median home prices have outpaced general CPI by a wide margin since the 1980s.
- College tuition has roughly tripled CPI inflation over the same period.
The long-run trend is real, but the categories are uneven. Always sanity-check sector-specific inflation against the headline figure when planning.