HomeMoney basicsInflation

A dollar, across decades.

Bureau of Labor Statistics CPI-U, 1913 to 2024.

$100 in 1990 equals
$240.21
Cumulative inflation: 140.2%
Annualized inflation2.6%
Years34
From CPI-U130.7
To CPI-U313.7
The math

Same dollar, different decade.

Inflation is the average rise in prices over time, measured in the US by the Bureau of Labor Statistics' Consumer Price Index for All Urban Consumers (CPI-U) — a basket of goods and services tracked monthly since 1913. To convert any past dollar amount to today's purchasing power: multiply by the ratio of current CPI to past CPI. The math compounds — small annual rates produce large multi-decade gaps. Average US inflation since 1913 has been ~3.2% per year, but the journey has included 1979's 13% peak, 2009's brief deflation, 2022's ~9% surge, and stretches of 1-2% near-stability.

Today's value = Past value × (CPI now ÷ CPI then)
Annualized inflation = (CPI now ÷ CPI then)1/years − 1
Real return = (1 + nominal) ÷ (1 + inflation) − 1
Worked example

$100 in 1990 vs 2024.

Scenario · BLS CPI-U annual averages
1990 CPI-U. 130.7. 2024 CPI-U. 313.7.
Equivalent 2024 value. $100 × (313.7 ÷ 130.7) = $240.21. The same purchasing power in 2024 dollars.
Cumulative inflation. ($240.21 ÷ $100 − 1) × 100 = 140.2% over 34 years.
Annualized rate. (240.21 ÷ 100)1/34 − 1 = 2.6% per year. Below the long-run 3.2% average — the 1990s and 2010s were notably calm.
Reverse direction. What's $100 of 2024 worth in 1990 dollars? $100 × (130.7 ÷ 313.7) = $41.66. A dollar today buys what 42 cents bought in 1990.
Decades feel slow but the math compounds aggressively. A "stable" 2.6% means doubling every ~27 years — every generation sees prices roughly double.
By era

US inflation, decade by decade.

EraAverage annual inflationNotes
1913-1945~2.0%WWI/WWII shocks, mid-decade deflation, no formal Fed target
1946-1965~2.0%Bretton Woods era — generally stable
1966-1982~7.5%Stagflation. 1980 peak: 13.5%
1983-1999~3.4%Volcker disinflation, gradual normalization
2000-2019~2.2%Globalization era, low inflation
2020-2024~4.7%Pandemic supply chain + fiscal stimulus surge to 9% in 2022

Long-run average since 1913: ~3.2%. The Fed's formal 2% PCE target dates to January 2012; before that, "low and stable" was the implicit goal without a numeric target.

Common mistakes

Where inflation math leads people astray.

Always think in real dollars for multi-decade plans

A "$2 million retirement" projected in 2055 nominal dollars sounds substantial — but at 3% inflation that's only ~$1M of today's purchasing power. Run all retirement, college-savings, and FIRE math in real (inflation-adjusted) dollars, or apply a discount rate at the end. Mixing nominal and real produces optimistic illusions.

Cash loses to inflation in real terms

HYSA at 4.3% APY at 3% inflation = real return of 1.3% — barely positive. T-bills yields below CPI produce negative real return (common during 2010s ZIRP era). Holding multi-decade emergency reserves in cash mathematically guarantees loss of purchasing power. The trade-off is liquidity vs growth — for emergency funds the trade is correct; for long-horizon savings, equities and TIPS protect better.

CPI and PCE are not interchangeable

The Fed's 2% target is on PCE inflation, which runs ~0.3-0.5 points lower than CPI inflation due to methodology differences (chain-weighting, broader basket, lower housing share). When news quotes "3.2% CPI" and "Fed has not yet hit its 2% target," the corresponding PCE figure is closer to 2.7% — much closer to target. Always check which measure is being cited.

Methodology

What's behind the data.

Assumptions
  • Annual averages of BLS CPI-U from 1913-2024 (most recent full-year data).
  • For partial years (e.g., 2025, 2026 mid-year), the calculator interpolates from the most recent annual average.
  • Calculation: equivalent value = principal × (target year CPI ÷ source year CPI). Annualized rate via CAGR formula on the same ratio.
  • Excludes regional CPIs (CPI for specific metro areas), CPI-W (wage earners — used for SS COLA), CPI-E (elderly experimental), and PCE (Federal Reserve preferred measure).
  • For real-return calculation in retirement/investing planning, use the (1+nom) ÷ (1+inf) − 1 formula rather than simple subtraction.
  • Hedonic and substitution adjustments built into BLS methodology — see BLS Handbook of Methods Chapter 17 for details.

Sources: US Bureau of Labor Statistics CPI-U series (CUUR0000SA0, all items, all urban consumers, US city average); BLS Handbook of Methods, Chapter 17 (CPI methodology); Federal Reserve FOMC Statement on Longer-Run Goals (2012, updated 2020); Bureau of Economic Analysis PCE methodology; Cleveland Fed median CPI / 16% trimmed-mean CPI; Robert Shiller online historical CPI data; Damodaran historical inflation series.

Glossary

Inflation vocabulary.

CPI
Consumer Price Index — BLS measure of average price change for an urban household basket.
CPI-U
CPI for All Urban Consumers — the standard reference series.
CPI-W
CPI for Urban Wage Earners — used for Social Security COLA.
PCE
Personal Consumption Expenditures price index — Fed's preferred inflation measure.
Core inflation
Headline inflation excluding food and energy. Less volatile, used for policy.
Nominal
Unadjusted dollar amount or rate.
Real
Inflation-adjusted dollar amount or rate. Reflects purchasing power.
OER
Owners' Equivalent Rent — proxy for owner-occupied housing inflation in CPI.
Hedonic adjustment
BLS quality-adjustment to prices when products improve.
TIPS
Treasury Inflation-Protected Securities — bonds whose principal adjusts with CPI.
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FAQ

Questions, asked plainly.

BLS measure of average price changes for a representative urban-household basket. Includes housing (~33%), food (~14%), transportation (~17%), medical (~8%), other. CPI-U is the standard reference; CPI-W drives Social Security COLA. Released monthly with ~2-week lag. Series since 1913 with revisions including 1983's shift to Owner's Equivalent Rent for housing.

Compounding inflation. Average annual US inflation 1980-2024 was ~3.0%, compounding to ~3.8× cumulative price increase over 44 years. $100 in 1980 = ~$382 in 2024 dollars; conversely, $100 in 2024 buys what $26 bought in 1980. The 1979-80 stagflation peak (~13%) and 2021-2022 spike (~7-9%) drove an outsized share of the increase.

Adopted formally January 2012 — 2% PCE inflation as part of the Fed's dual mandate (price stability + max employment). PCE runs ~0.3 points lower than CPI. Above 2% PCE → Fed tightens. The 2021-2022 surge to ~9% CPI / 7% PCE drove the most aggressive tightening since the 1980s. Through 2025-26 both measures gradually returning toward target.

Both measure prices but differ. CPI (BLS): fixed basket updated every 2 years, ~33% housing share. PCE (BEA, Fed-preferred): chain-weighted basket updated monthly, ~15-20% housing share, broader "consumed by households" definition including employer-provided healthcare. PCE typically prints 0.3-0.5 points lower. Fed's 2% target is on PCE. News usually quotes CPI because released earlier.

Headline includes everything in the basket. Core excludes food and energy — both highly volatile due to weather, geopolitics, oil shocks. Core is a better measure of underlying trends and what monetary policy primarily targets. 2022 example: headline CPI peaked at 9.1%, core peaked at 6.6%. Trim-mean and median CPI (Cleveland Fed) exclude only the extreme components in any given month.

Erodes real (purchasing-power) value of nominal amounts. 4% HYSA at 3% inflation = 0.97% real — barely keeping up. S&P 500's 10% nominal long-run = 7% real. Cash and short bonds typically lose to inflation over decades; equities, real estate, and TIPS are the main classes that beat inflation reliably. Real return = (1 + nominal) ÷ (1 + inflation) − 1. Plan multi-decade goals in real dollars.

TIPS (Treasury Inflation-Protected Securities): US Treasuries whose principal adjusts with CPI-U. Pay fixed real coupon on inflation-adjusted principal. Effectively zero-real-yield insurance. I Bonds (Series I): TreasuryDirect-only savings bonds with composite rate (fixed real + CPI variable). Capped $10k/yr per SSN. Simpler for retail (no broker, no markup) but 12-mo minimum hold and lose 3 mo interest if redeemed before 5 years.

No — modern targets are recent. 1913-1945: WWI/WWII shocks. 1946-1965: Bretton Woods ~2%. 1966-1982: stagflation, 13.5% peak 1980. 1983-2007: Volcker disinflation ~3%. 2008-2020: ~1.8% (some deflation fears). 2021-2022: pandemic surge to ~9%. 2023-2025: gradual return to target. The "normal 3%" expectation is a 1980-2020 averaging artifact.

BLS methodology adjustments. Hedonic: when product quality improves (faster computers), BLS adjusts price for the quality increase. Substitution bias: when consumers switch to cheaper alternatives (chicken instead of beef), fixed-basket CPI overstates true cost-of-living impact. PCE addresses substitution via chain-weighting; CPI partially via biennial basket updates. Critics argue these understate experienced inflation; defenders argue they correct genuine measurement errors.

Several reasons. (1) CPI is an average; specific demographics experience differently. (2) Salience bias: rising prices more visible. (3) Cumulative effect: 25% rise over 5 years feels jarring even at 4.5% annual. (4) Sticky baseline: people remember pre-inflation prices for years. (5) Asset price inflation (housing, education) partly excluded — OER captures rental but not home-buying prices.