Planning

What Is Inflation and How It Quietly Erodes Your Money

March 20, 20255 min read

Inflation doesn't show up in your bank statement. Your balance stays the same while everything you can buy with it quietly shrinks. $100,000 sitting in a zero-interest account for 10 years at 3% inflation is worth $74,000 in real purchasing power. No theft, no market crash — just time and rising prices doing their work.

How Inflation Is Measured

The most common measure is the Consumer Price Index (CPI) — a basket of goods and services that typical households buy. When the CPI rises 3%, that basket costs 3% more than it did a year ago.

CPI (All Items): broad inflation including food, energy, housing, transportation
Core CPI: excludes food and energy (more stable, used for policy)
PCE (Personal Consumption Expenditures): the Fed's preferred measure — tends to run slightly below CPI

Your personal inflation rate may differ significantly from reported CPI. If you rent in an expensive city, your housing inflation could be 8–10% while CPI prints 3%. CPI is an average across millions of households — not necessarily your household.

The Purchasing Power Effect Over Time

At different inflation rates, here's what $100,000 of purchasing power looks like over 10 and 20 years:

2% inflation → $82,000 after 10 years, $67,000 after 20 years
3% inflation → $74,000 after 10 years, $55,000 after 20 years
5% inflation → $61,000 after 10 years, $38,000 after 20 years

The "lost" purchasing power doesn't disappear — it transfers to whoever benefits from rising prices (sellers, borrowers with fixed-rate debt). Holding cash long-term means being on the losing side of that transfer.

What Protects Against Inflation

Not all assets lose to inflation equally. Some naturally keep up; others significantly outpace it:

Stocks (equities): historically ~7% real return after inflation over the long run
Real estate: property values and rents tend to rise with inflation
TIPS (Treasury Inflation-Protected Securities): principal adjusts with CPI
I-Bonds: US government bonds with inflation-linked interest rates
High-yield savings (short term): when rates are above inflation, cash holds value

Bonds (fixed rate): lose real value in high inflation — fixed payments buy less over time
Cash and low-interest savings: guaranteed real-value loss when inflation exceeds yield

Inflation and Debt: The One Upside

Inflation helps borrowers with fixed-rate debt. If you have a 30-year mortgage at 4% and inflation runs 3%, your real interest rate is only 1%. The nominal dollar amount you owe stays fixed while prices — and ideally your income — rise. Historically, long-term fixed-rate mortgage borrowers benefited from inflation eroding the real value of their debt.

This is why locking in a fixed-rate mortgage at a low rate during low-inflation periods is valuable — and why adjustable-rate debt is riskier when inflation rises. The rate adjusts; the inflation benefit disappears.

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Frequently asked questions

Is some inflation actually good?

Most central banks target 2% annual inflation. Mild inflation encourages spending and investment (money loses value sitting idle) and gives central banks room to cut rates in downturns. Deflation — falling prices — is generally worse: it causes consumers to delay purchases and can trigger economic contraction.

How should I adjust retirement savings for inflation?

Use real (inflation-adjusted) returns in your projections. If your investments return 8% nominal and inflation is 3%, your real return is about 5%. A $1,500,000 portfolio at retirement sounds different depending on what it buys. Run projections in today's dollars to stay grounded.

Does inflation affect Social Security benefits?

Yes, positively. Social Security has an annual Cost of Living Adjustment (COLA) tied to CPI. In high-inflation years, benefits increase — 8.7% in 2023, for example. This makes Social Security unusually inflation-resistant compared to other fixed income sources like traditional pension annuities.

What was the highest US inflation rate in history?

During World War II, US inflation peaked above 20% annually. In recent decades, the 1970s oil shocks pushed inflation above 13% in 1979. The 2022 peak was 9.1% CPI — the highest since 1981. Since 1990, average annual CPI has been around 2.5–3%.

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