How it's calculated
Average yearly inflation = (CPI(B) ÷ CPI(A))1 ÷ years − 1
CPI is the Consumer Price Index for All Urban Consumers (CPI-U), U.S. city average, all items, not seasonally adjusted (BLS series CUUR0000SA0, 1982–84 = 100). A year uses that year's annual average. A 2026 month uses that month's index.
For the yearly average rate, an annual average counts as the middle of its year and a month counts as the middle of that month. So 1970 to September 2026 is about 56.2 years.
Worked example
$100 in 2000 in 2025 money: the CPI-U averaged 172.2 in 2000 and 321.943 in 2025. 100 × 321.943 ÷ 172.2 = $186.96. Prices rose 87.0% in total, which is 2.53% a year on average over 25 years.
Selected CPI-U values
| Period | CPI-U | Period | CPI-U |
|---|---|---|---|
| 1913 | 9.9 | 2000 | 172.2 |
| 1950 | 24.1 | 2010 | 218.056 |
| 1970 | 38.8 | 2020 | 258.811 |
| 1980 | 82.4 | 2025 | 321.943 |
| 1990 | 130.7 | September 2026 | 336.940 |
Latest data: September 2026 (released October 14, 2026). BLS didn't publish a CPI for October 2025 because of the lapse in federal funding. For that reason BLS's 2025 annual average is the average of the 11 months it did publish.
When it doesn't fit
- CPI-U measures an average basket of goods for city households. Your own costs may have risen faster or slower. Housing, college and health care have often beaten the average.
- Annual averages smooth out changes within a year. For an exact month, use a monthly index.
- Before 1940 the index covered fewer items and cities, so early figures are rougher.
- This isn't the inflation rate used for Social Security raises (that uses CPI-W) or for tax brackets (which use chained CPI).
Sources
- BLS Consumer Price Index – CPI-U, U.S. city average, all items (CUUR0000SA0)
- BLS CPI supplemental files (historical CPI-U) – historical CPI-U table, 1913 to date
- BLS CPI news release, Table 1 – September 2026 index: 336.940