Inflation Calculator
See what inflation has actually done — and what it might do next. The Historical (CPI) mode converts dollars between any two years from 1913 to 2025 using official US CPI-U annual averages: what $100 in 1990 buys today, the cumulative price change, and the average annual rate. The Projection mode compounds an assumed rate forward to show what you'll need to keep the same buying power. All in your browser.
Historical mode uses official US CPI-U annual averages from the Bureau of Labor Statistics (1913–2025; the 2025 figure is preliminary). For example, $100 in 1990 bought what about $240 buys in 2024. Projection mode is an assumption at the rate you choose — long-run US inflation has averaged around 3%.
What was $X worth? The historical answer
Questions like "what is $100 in 1990 worth today?" have an exact answer, because the Bureau of Labor Statistics has measured consumer prices since 1913. The historical mode divides the CPI of the target year by the CPI of the starting year and scales your amount: $100 in 1990 ≈ $240 in 2024 dollars. It works in both directions — convert grandpa's 1955 salary into today's money, or today's rent back into 1970s dollars — and it reports the average annual inflation between the two years, which is often more telling than the headline multiple. Source: BLS CPI-U annual averages (the 2025 figure is preliminary).
Inflation is compounding in reverse
The same math that makes savings grow makes prices climb — it just works against you. At 3% a year, prices don't rise 3% once; they rise 3% on top of last year's higher prices, every year. Over a few decades that compounding is dramatic: by the rule of 72, a 3% rate roughly doubles prices every 24 years. The number that looks comfortable today can look thin by retirement.
Two ways to read the erosion
There are two honest ways to state the same loss. One: the future price — what you'll need to buy the same thing later. Two: future buying power — what your fixed amount will actually buy later, in today's dollars. A $1,000 expense at 3% becomes about $1,806 in 20 years; equivalently, $1,000 stashed in cash for 20 years buys only what about $553 buys now. Same erosion, framed from either end.
Why this is the case for investing
Inflation is the quiet argument against keeping long-term money in cash. If a savings account pays 1% while inflation runs 3%, you lose purchasing power every year even though the balance number goes up. The goal isn't a positive nominal return — it's a positive real return, after inflation. That's why long-horizon savings usually belong in investments that have historically outpaced inflation.
Related
- Personal finance hub — all our money calculators and guides
- Compound interest calculator — growth that can outpace inflation
- ROI calculator — measure returns to compare against inflation
- FIRE calculator — uses real (after-inflation) returns
FAQ
Is anything I enter sent to a server?
No. The calculator runs entirely in your browser — open DevTools → Network and confirm. Nothing you type is uploaded.
Does this use real historical inflation (CPI) data?
Yes — the Historical (CPI) mode uses the official US CPI-U annual averages published by the Bureau of Labor Statistics, covering every year from 1913 to 2025 (the 2025 figure is preliminary). Pick any two years and it converts dollars between them in either direction: value = amount × CPI[to] ÷ CPI[from]. The Projection mode is the forward-looking counterpart — an assumed flat rate for future planning, since nobody knows next decade's CPI.
What is $100 in 1990 worth today?
About $240 in 2024 dollars — prices roughly 2.4× over that stretch, an average of about 2.6% inflation a year. The historical mode answers this instantly for any pair of years: $100 in 1950 ≈ $1,300 today; $100 in 1980 ≈ $390. It also works backward — enter today's amount with a recent "from" year and an older "to" year to see what a sum corresponds to in past dollars.
What inflation rate should I assume?
Long-run US inflation has averaged roughly 2–3% per year, and many central banks target about 2%. But it swings — there are years near zero and years above 8%. A reasonable planning default is 3%. If you're stress-testing, run a higher rate too and see how much the future number moves.
What's the difference between the two numbers?
The headline ("you'll need") is how many future dollars it takes to buy what your amount buys today — prices going up. The grid's "future buying power" is the flip side: what your fixed amount will actually buy down the road, expressed in today's dollars — your money buying less. Same erosion, two viewpoints.
Why does inflation matter so much over long periods?
Because it compounds, just like investment returns — only against you. At 3%, prices roughly double every 24 years (the rule of 72: 72 ÷ 3). Money sitting in cash loses purchasing power every year, which is the core argument for investing long-term savings rather than holding it all in cash.
How does this relate to investment returns?
Directly. If your investments earn 6% and inflation is 3%, your real return is only about 3%. Beating inflation is the whole point of investing — a "safe" 1% savings account actually loses purchasing power when inflation is 3%. Pair this with the compound interest and ROI calculators to see the real picture.