How purchasing power works
Purchasing power is the other side of the price level. Inflation measures how much more the same things cost; purchasing power measures how much less a fixed sum of money buys. The two are not quite the same number. If prices rise 3.4%, as the CPI-U did in the 12 months ending August 2026, a dollar buys 1 ÷ 1.034 of what it did, about 96.7%, so its purchasing power fell by 3.3%, not 3.4%. The gap grows with higher inflation. In Deflation, the process runs in reverse and each dollar buys more.
The Bureau of Labor Statistics publishes a series called the purchasing power of the consumer dollar, set at $1.00 for the 1982–84 average and calculated as the Consumer Price Index turned upside down. By August 2026 it stood at 29.9 cents. That does not mean a dollar is worth 30 cents today; it means today’s dollar buys what 29.9 cents bought four decades ago.
What matters is what money buys, not the number on the statement. A savings balance that earns 2% while prices rise 3.4% grows in dollars but shrinks in purchasing power. That is the difference between a nominal interest rate and a real rate of return.
How to convert dollars between years
To compare money from different years, restate it in one year’s prices using the ratio of their price index levels. BLS runs a CPI Inflation Calculator that does exactly this with the CPI-U. It shows that $100 in August 2006 had the same buying power as $164.29 in August 2026, and $100 in August 1996 the same as $212.96. Turned around, $100 today buys what about $60.87 bought in August 2006.
For future dollars there is no index yet, so planners assume an inflation rate and divide: an amount n years away is worth that amount ÷ (1 + inflation)^n at today’s prices. This looks like discounting in the time value of money, but the purpose differs. Dividing by inflation tells you what money will buy; discounting at a rate of return tells you what money is worth to you as an investment.
When you read long-range projections, check which basis they use. A retirement plan showing $3 million at age 90 in future dollars may buy well under half that much at today’s prices, depending on the inflation assumed and how many years away age 90 is.
Why fixed incomes lose ground
Any payment that stays the same number of dollars loses purchasing power every year that prices rise. At 3% inflation, a $2,000 monthly Pension with no increases buys what about $1,488 does today after 10 years and about $955 after 25, as the example below shows. Level immediate annuities, fixed pensions and bond interest all behave this way.
Income with a cost-of-living adjustment behaves differently. Social Security raises benefits each year by the change in the CPI-W, 2.8% for benefits paid from January 2026, and does not cut them when prices fall. Because it tracks prices, a dollar of Social Security income keeps roughly the same purchasing power over a retirement, while a dollar of fixed pension income fades. That is why two income streams that start at the same amount are not worth the same.
The longer the retirement, the bigger the gap. A couple retiring at 62 may need their income to hold its value into their 90s, which is three decades of compounding for inflation to work on.
Purchasing power across places
Purchasing power also varies by where you live, because price levels differ from place to place. The Bureau of Economic Analysis measures this with regional price parities, which set the national price level at 100. In 2024, California stood at 110.7 and Hawaii at 110.0, while Arkansas was 86.9 and Mississippi 87.0. The same income therefore bought about 27% more in Arkansas than in California (110.7 ÷ 86.9). Housing costs vary the most: across states, the parity for rents ranged from 154.3 in California to 54.2 in West Virginia.
This is the idea behind Geoarbitrage, moving to a lower-cost area to stretch a fixed income or portfolio. The price gap is only part of the math, though: state taxes, health coverage and the cost of the move itself can offset some of it.
Illustrative numbers
What a fixed $2,000 monthly pension buys at 3% inflation
- Nominal amount
- Dollars as paid, earned or quoted in their own year
- CPI in the base period
- The index for the year whose dollars you want to express the amount in
- CPI in the period paid
- The index for the year the amount was actually paid or received
For future amounts, replace the CPI ratio with 1 ÷ (1 + assumed inflation)^years.
Monthly payment, never increased$2,000
Buying power after 10 years (÷ 1.3439)$1,488
After 20 years (÷ 1.8061)$1,107
After 25 years (÷ 2.0938)$955
Buying power lost by year 25About 52%
The check never shrinks, but by year 25 it buys less than half of what it did at the start. A payment with a cost-of-living adjustment avoids most of that drift, which is why planners compare income streams at today’s prices rather than by their starting amounts.
At a glance
What $100 from past years is worth in August 2026 dollars (CPI-U, August of each year)
| Year | CPI-U | $100 then equals, August 2026 | Buying power a dollar has lost since |
|---|---|---|---|
| 1976 | 57.4 | $583.59 | 82.9% |
| 1986 | 109.7 | $305.36 | 67.3% |
| 1996 | 157.3 | $212.96 | 53.0% |
| 2006 | 203.9 | $164.29 | 39.1% |
| 2016 | 240.849 | $139.08 | 28.1% |
| 2021 | 273.567 | $122.45 | 18.3% |
| 2025 | 323.976 | $103.40 | 3.3% |
Put it in your plan
Purchasing Power in MoneyWhatIf
MoneyWhatIf settles every plan year in that year’s own dollars. The Today’s money switch then divides each figure by the plan’s cumulative inflation, 3% a year unless you change it, to show what it would buy at today’s prices: at 3%, $100,000 in year 11 displays as about $74,400. Taxes are not recalculated. Each income or spending entry can stay flat in dollars, which loses purchasing power, or follow inflation, which keeps it. Reports and their downloads can use the same basis and print which one they show.
Common questions
Purchasing Power FAQs
What is the difference between nominal and real dollars?
Nominal dollars are the amounts actually paid or quoted in their own year. Real, or constant, dollars restate those amounts in the prices of a single base year, so they can be compared fairly. A salary that grew from $50,000 to $70,000 over a decade rose 40% in nominal terms; whether it rose in real terms depends on how much prices climbed over the same decade.
Does a raise increase my purchasing power?
Only if it beats inflation. A 4% raise in a year when prices rose 3.4% lifts your purchasing power by about 0.6%, because 1.04 ÷ 1.034 is about 1.006. A 3% raise in the same year would leave you slightly worse off in what your pay buys, even though the paycheck is bigger. Comparing raises with the CPI is the simplest check.
How do you compare salaries between states with different costs?
Scale one salary by the ratio of the two areas’ regional price parities. With BEA’s 2024 state figures, a $100,000 salary in California (110.7) buys about what $78,500 does in Arkansas (86.9), because 100,000 × 86.9 ÷ 110.7 is about 78,500. BEA also publishes parities for metro areas, which are closer to where you would actually live. Taxes, housing choices and benefits still differ, so treat the result as a starting point.
What is purchasing power parity?
Purchasing power parity (PPP) compares what money buys in different countries. A PPP exchange rate is the rate at which two currencies would buy the same basket of goods and services in each country, which can differ a lot from the market exchange rate. Economists use PPP figures to compare incomes and living standards across countries, and the same idea explains why a retirement budget can stretch further abroad.