How this inflation calculator works
Historical mode divides the Consumer Price Index of the target month by the index of the starting month and multiplies your amount: value = amount × CPIto ÷ CPIfrom. The data — every month from January 1913 through August 2026, 1,363 index values — comes from the US Bureau of Labor Statistics (series CUUR0000SA0, 1982–84 = 100), the same official series behind Social Security COLAs and IRS bracket indexing.
Month-level precision matters when the comparison is tied to a date: a salary you were paid in a given month, an alimony or pension clause, a contract that escalates with CPI, or a court award. Comparing annual averages instead can move the answer by a percent or more in a volatile year.
A century of the dollar, in one table
What $100 in August of each year is worth in August 2026 dollars:
| August of | $100 then = now | Cumulative inflation |
|---|---|---|
| 1913 | $3,384 | 3,284% |
| 1950 | $1,379 | 1,279% |
| 1970 | $859 | 759% |
| 1980 | $402 | 302% |
| 1990 | $255 | 155% |
| 2000 | $194 | 94% |
| 2010 | $153 | 53% |
| 2020 | $129 | 29% |
Why inflation matters for your money
Inflation has averaged about 3.2% a year since 1913 and 2.6% over the last 30 years. At 3%, prices double roughly every 24 years, so cash held outside an interest-bearing account loses half its purchasing power over the same span. That is why comparing salaries, house prices or investment returns across years means little without a CPI adjustment, and why savings have to out-earn inflation just to break even. Pair this with the compound interest calculator to see growth after inflation, or the take-home pay calculator to check whether a raise beat it.
Frequently asked questions
How much is $100 in 1990 worth today?
About $263 in August 2026 dollars, using CPI-U for January 1990 (127.4) against August 2026 (334.980) — cumulative inflation of roughly 163%.
What is the current US inflation rate?
CPI-U rose 3.4% in the 12 months ending August 2026, the most recent month BLS has published. The index was 334.980, against 323.976 a year earlier.
Where does the data come from?
BLS series CUUR0000SA0 — CPI for All Urban Consumers, all items, US city average, not seasonally adjusted, 1982–84 = 100 — pulled straight from the BLS public API. New months are added after each BLS release.
What's the average US inflation rate?
About 3.2%/year since 1913 and 2.6%/year over the past 30 years, with spikes in the late 1970s and a post-pandemic peak of 9.1% in June 2022.
Why do monthly and annual figures differ?
An annual figure averages twelve monthly values, smoothing swings inside the year. Month-to-month comparisons — how raises, contracts and COLAs actually work — often give a larger number.
Can I project future inflation?
Yes. Switch to projection mode and set any rate. The Federal Reserve targets 2%, while the realized average over the last 30 years was 2.6%.