Inflation Calculator · BLS CPI-U 1913-2024 + Fisher Equation — Vectobox
Free inflation calculator with official BLS CPI-U history (1913-2024), Fisher equation real return (exact vs approximation side-by-side), Chained CPI-U toggle for post-TCJA tax indexing, and compound future-value projection. Pure browser, zero tracking.
Pure browser. Zero upload. Your numbers never leave this tab.
Standard BLS series. Tracks overall urban consumer price level.
Formula & source
A × CPI[end] / CPI[start]BLS CUUR0000SA0 — Historical CPI-U 1913–2024Why two real-return numbers?
Irving Fisher's 1930 equation states `(1+i) = (1+r)(1+π)` — so the exact real rate is `r = (1+i)/(1+π) − 1`. Most online tutorials simplify to `r ≈ i − π`, which is fine when both rates are small. When inflation and yields climb (think 1970s, or emerging-market hyperinflation), the cross-product `r·π` makes the approximation drift by tens to hundreds of basis points. This tool always shows both side-by-side so you can decide whether the difference matters in your context.
Where does the CPI data come from?
The historical series is the Bureau of Labor Statistics CPI-U All Urban Consumers (series id `CUUR0000SA0`), annual averages 1913–2024, base period 1982–1984 = 100, copied 1:1 from the BLS December 2024 supplemental file. Chained CPI-U comes from series `SUUR0000SA0`, annual averages 2000–2024, base December 1999 = 100. No third-party API, no network calls.
When should I use Chained CPI-U?
The Tax Cuts and Jobs Act 2017 (TCJA §11002) switched IRS tax-bracket and standard-deduction indexing from CPI-U to Chained CPI-U starting in 2018. C-CPI-U accounts for consumer substitution effects and drifts roughly 0.25%/yr lower than CPI-U. Use Chained CPI-U if you're modelling tax brackets, TIPS coupons indexed after the TCJA, or Social Security COLAs proposed under the 2013 chained-CPI-U reform. Use CPI-U for everything else.
Linear vs compound trap
"10% inflation for 5 years = 50% cumulative" is one of the most common back-of-envelope errors. The correct compound figure is `(1+0.10)^5 − 1 = 61.05%` — a gap of 1105 bps. The Future Value tab surfaces a warning whenever `π × years` exceeds 25% so the linear trap stays visible.
FAQ
- Why does this show two different real-return values?
- One is Irving Fisher's exact formula `r = (1+i)/(1+π) − 1`, the other is the simplified approximation `r ≈ i − π`. They are within a few basis points at low rates but diverge by hundreds of bps in high-inflation scenarios. Showing both makes the cross-product term r·π — which most calculators silently drop — visible.
- Is the CPI data official BLS?
- Yes. CPI-U 1913–2024 annual averages come from the BLS Historical CPI-U December 2024 supplemental file (series CUUR0000SA0). Chained CPI-U 2000–2024 comes from series SUUR0000SA0. The arrays in this tool are copied 1:1; cross-check the key anchor years (1980=82.4, 2000=172.2, 2024=313.689) against the BLS PDF.
- When should I use Chained CPI-U vs CPI-U?
- Chained CPI-U is the index the IRS uses for tax bracket and standard-deduction inflation indexing since TCJA 2017 (Rev. Proc. 2018-57). It drifts about 0.25%/yr lower than CPI-U. Use it when modelling tax brackets, TIPS post-TCJA, or any IRS indexing scenario; use plain CPI-U for general purchasing-power questions and historical comparisons before 2000.
- Is my data sent anywhere?
- No. Every CPI lookup, Fisher calculation, and compound-factor expansion runs in your browser. There are no network requests, no analytics on the numbers you enter, and no third-party scripts on the result calculations.
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