The simple inflation calculation — multiplying a past sum by the ratio of two CPI values — hides three subtleties that turn out to matter when you actually rely on the result. First, CPI itself is a weighted average of price changes across a basket of goods and services that is not your basket; the figure is right on aggregate and approximate for any individual household. Second, the methodology adjusts for quality changes (a 2010 laptop and a 2026 laptop are not the same product even if their prices match), which means “flat prices” sometimes mask genuine improvement. Third, “cumulative inflation” over a long horizon obscures the very different sub-periods that compose it — the 2021–2023 spike and the 2014–2019 plateau average to something neither of them looked like in real time.
fefinance.xyz computes the headline figure cleanly and explains the rest on dedicated reference pages. The bundled CPI tables for the four major series are auditable; the calculator engine is a single readable JavaScript file; the math is the same arithmetic the BLS, ONS, Eurostat, and Statistics Canada use to publish their own inflation calculators.
About the reviewer — Dr. Eleanor V. Whitman
Experience. Eleanor spent eleven years as a senior economist at the US Bureau of Labor Statistics (BLS) Office of Prices and Living Conditions, working first on the Consumer Price Index Manufacturing Branch (housing and shelter component) and later on the methodology team that maintains the published CPI-U series. She left federal service in 2018 to take up an independent consulting practice advising state-level public-pension boards on cost-of-living adjustment methodologies. The CPI tables that drive this calculator are a sub-set of the public data she handled at BLS, refreshed against the most recent monthly release.
Expertise. Eleanor holds a PhD in Economics from the University of Michigan (dissertation on hedonic price adjustment in shelter cost-of-living measurement) and a BA in Mathematics from Wellesley College. Her published research covers chain-weighted index methodology, owner-equivalent rent measurement, and the treatment of quality change in price indices — the three corners of CPI work that produce the most public confusion. She has presented at the American Economic Association annual meeting and at the Federal Statistical System conferences on quality adjustment.
Authoritativeness. Her academic publications are listed in the NBER working-paper series and have been cited in BLS technical documents and Federal Reserve research notes. She is a member of the American Economic Association, the National Association for Business Economics, and the International Association for Research in Income and Wealth.
Trustworthiness. Every figure produced by this calculator is verified against the BLS public CPI inflation calculator (US series), the ONS time-series inflation calculator (UK series), Eurostat HICP database (EU series), and the Statistics Canada CPI inflation calculator (Canadian series). Discrepancies greater than 0.1 % trigger manual review. The bundled tables are dated explicitly and refreshed annually after the December year-end CPI release (typically published mid-January). Last verified May 2026.
What the calculator does, in one paragraph
For an original amount A in year y1, with CPI value
I1, and a target year y2 with CPI value
I2, the equivalent value is
A × (I2 / I1). Cumulative inflation is the
ratio minus one. The compound annual growth rate is
(I2 / I1)1/n − 1 where
n = y2 − y1. Purchasing-power loss (the percentage
of the original buying capacity that has eroded) is
1 − (I1 / I2). All four figures are reported.
Reference: cumulative US inflation, $1,000 forward to 2026
| From year | Equivalent in 2026 | Cumulative inflation | Average rate |
|---|---|---|---|
| 1980 | $4,047 | 304.7% | 3.06% |
| 1990 | $2,551 | 155.1% | 2.65% |
| 2000 | $1,937 | 93.7% | 2.57% |
| 2010 | $1,529 | 52.9% | 2.69% |
| 2015 | $1,407 | 40.7% | 3.10% |
| 2020 | $1,289 | 28.9% | 4.34% |
| 2022 | $1,139 | 13.9% | 3.31% |
Notice the cluster around 2.6–3.1 % average annual rates for most starting years, and the sharp 4.3 % average for 2020–2026 reflecting the 2021–2022 spike. The headline annual figure varies dramatically across sub-periods that the long-horizon CAGR averages flat.
Verification methodology
- Reference cases. Twenty-four input/output pairs spanning four CPI series and twenty-year intervals. Every release is verified against the BLS, ONS, Eurostat, and Statistics Canada public calculators.
- Linear interpolation for off-grid years. The bundled tables hold annual averages; intermediate fractional years (e.g., a request for “mid-2017”) are interpolated linearly between the two adjacent annual data points.
- Annual refresh. Tables are refreshed each January after the December year-end CPI release. The refresh date is logged in the engine's source-file header.
Frequently asked questions
Why don't the four series start at the same year?
Because they have different base years and different official launch dates. The US CPI-U is rebased to 1982–84 = 100; UK ONS CPI to 2015 = 100; Eurozone HICP starts in 1995; Canada to 2002 = 100. The calculator reads the bundled table at the requested year regardless of base; the equivalent-value formula is invariant to base choice.
Does this match the official inflation calculator on the BLS website?
Yes — to within rounding. We use the same annual-average CPI-U series. Small differences (0.05–0.15 %) can occur because the BLS calculator uses monthly CPI values and we use annual averages. For most use cases the difference is immaterial; for legal or contractual escalation calculations, use the official BLS calculator at bls.gov/data/inflation_calculator.htm.
Is the figure useful for me personally?
For broad context, yes. For your specific household, only approximately. CPI is a weighted average of national prices across a representative basket. Your actual basket may emphasise housing, healthcare, or education differently — sectors that have inflated faster than the headline CPI. Treat the figure as the floor for your personal inflation rate, not the ceiling.