How Inflation Erodes Savings and Purchasing Power

The nominal balance is the number on the statement. The real value is what that balance buys, measured in the prices of some earlier year. To convert, multiply the balance by the ratio of the two years' CPI levels: real value = balance × CPI_start ÷ CPI_now. That ratio is all the Inflation Calculator does.

With a steady 3% inflation rate, $10,000 held in cash buys what $7,441 bought at the start after 10 years, $5,537 after 20 years, and $4,120 after 30. Each year the balance loses about 2.9% of the purchasing power it had left (1 − 1/1.03), so the dollar loss is largest in the early years and shrinks as the base gets smaller.

What compounds is the price level. At 3% a year, prices rise 34% in 10 years, 81% in 20, and 143% in 30, well above the 30%, 60%, and 90% that simple addition suggests. At that rate prices double, and the purchasing power of idle cash halves, in about 23 years; the rule of 72 (72 ÷ 3 = 24) gives a close estimate.

Short bursts of high inflation move the level permanently. CPI rose 4.7% in 2021 and 8.0% in 2022, a combined 13.1% on annual averages. Inflation slowed to 4.1% in 2023, but slower inflation means prices rise more slowly; it does not bring them back down. Cash held through those two years kept the lower real value it ended with.

Interest offsets part of the loss. The real return is approximately the interest rate minus the inflation rate; the exact figure is (1 + interest) ÷ (1 + inflation) − 1. An account paying 2% during 3% inflation has a real return of about −1%: the balance grows and its purchasing power shrinks.

In recent years the average savings account has paid far less than inflation. The FDIC's national average savings rate was 0.06% to 0.30% during 2022 and never exceeded 0.5% from 2021 through 2025, even while the Federal Reserve held its policy rate at 5.25% to 5.50% from July 2023 to September 2024. Over those years annual CPI inflation ran between 2.6% and 8.0%, so money in an average savings account lost real value every year. In 2022, with the average account paying about 0.13% and CPI up 8.0%, the real return was about −7.3%.

The IRS taxes interest on its full nominal amount, including the portion that only replaces purchasing power lost to inflation. Take an account paying 5% while inflation runs 3%, held by someone in the 22% federal bracket. The pre-tax real return is about 1.9%. Tax takes 1.1 points of the 5%, leaving 3.9%, and the after-tax real return falls to about 0.9%. If inflation were 4% instead, the same account would lose about 0.1% a year after tax and inflation. State income tax on interest lowers it further.

The break-even interest rate is inflation ÷ (1 − tax rate). At 3% inflation and a 22% bracket that is 3.85%; anything less loses purchasing power after tax. Federal brackets and the standard deduction have been indexed to inflation since 1985, which limits bracket creep on wages, but the tax on interest and on capital gains is still figured on nominal amounts.

None of this makes cash the wrong place for an emergency fund or for money needed within a year or two. Over a short period the expected inflation loss is a few percent, smaller than the swings a stock or long-term bond fund can show in the same time. The cost is real but measurable, and the table above shows how it grows with the holding period.

Some instruments are built to offset the loss: I bonds and TIPS are indexed to the CPI, and money market funds and high-yield savings accounts pay rates that follow the federal funds rate. The guide on protecting savings from inflation covers how each one works, its limits, and when it falls short.

A pension or annuity that pays the same dollar amount every month loses purchasing power the same way a cash balance does. A fixed $2,000 monthly payment that began in 2006 buys what $1,214 bought in 2006, after prices rose 65%. A retirement that starts in the early 60s and runs past 90 lasts about 30 years; over the 30 years to 2026, prices rose 112%.

Social Security benefits are adjusted each year by the change in the CPI-W, a CPI variant for wage earners; the adjustment paid from January 2023 was 8.7%, reflecting 2022's inflation. Many private pensions and most fixed annuities have no automatic adjustment, so their real value depends entirely on how prices move after payments begin.