Inflation: The Silent Threat to Your Retirement
Inflation erodes purchasing power over time. A 3% annual inflation rate — roughly the U.S. historical average — cuts the value of a dollar in half over 24 years. For retirees who may live 30–40 years in retirement, this isn't an abstract concern.
What Inflation Actually Is
Inflation is a general increase in the price level over time. When inflation runs at 3%, something that costs $100 today will cost $103 next year and $134 in 10 years.
The Federal Reserve targets roughly 2% annual inflation. The actual historical average since 1913 has been closer to 3%. The 2021–2023 period saw inflation spike to 7–9%, a level not seen since the early 1980s.
Real vs. Nominal Returns
Investment returns are quoted as nominal returns — the number you see on your brokerage statement. But what matters for purchasing power is the real return, adjusted for inflation.
Real return ≈ Nominal return − Inflation rate
If your portfolio returned 9% in a year with 3% inflation, your real return was approximately 6%. Your account balance grew 9%, but goods and services are 3% more expensive — so you can actually buy 6% more with your money than you could a year ago.
This is why retirement planning — including this calculator — uses real (inflation-adjusted) return assumptions rather than nominal ones. A 7% real return assumption means you expect 7% more purchasing power per year, not 7% more nominal dollars.
The Purchasing Power Cliff
The math of compound inflation is easy to underestimate:
| Years | Purchasing power of $1 at 3% inflation |
|---|---|
| 10 | $0.74 |
| 20 | $0.55 |
| 30 | $0.41 |
| 40 | $0.31 |
A retiree who lives 35 years past retirement sees their fixed expenses (in real terms) remain constant, but if their income is fixed in nominal terms, they lose roughly 65% of its purchasing power.
This is why fixed-income streams (like pensions without cost-of-living adjustments) erode over long retirements. Social Security, notably, includes annual cost-of-living adjustments (COLAs) tied to inflation — which is part of what makes it so valuable.
Categories That Inflate Faster Than Average
Not all expenses inflate at the same rate. For retirees, two categories consistently outpace headline inflation:
Healthcare: Medical inflation has historically run 1–2 percentage points above general CPI. For retirees who don't have employer-sponsored insurance, this is a significant planning variable.
Housing: Rents and home prices in many markets have outpaced inflation significantly. Owning a home outright provides protection against rent inflation; renters face more exposure.
Long-term care costs are a particular outlier — a wildcard that can absorb significant assets quickly.
Inflation Hedges
Equities (long-run): Over long periods, stocks tend to outpace inflation because companies raise prices along with inflation, protecting earnings. This is why a mostly-equity portfolio remains the standard FIRE recommendation — bonds and cash lose purchasing power over decades; equities generally don't.
TIPS (Treasury Inflation-Protected Securities): U.S. government bonds with principal that adjusts with CPI. They provide direct inflation protection, at the cost of lower expected return than equities.
I-Bonds: U.S. savings bonds with interest rates that include an inflation component. Subject to purchase limits ($10,000/year per person) but useful for the emergency fund layer.
Real estate: Rental income often rises with inflation; owned property protects against rising rent. Illiquid and management-intensive compared to index funds.
The Inflation Rate in This Calculator
The default inflation rate in the calculator reflects the approximate long-run U.S. average. Adjusting it higher (3.5–4%) gives you a more conservative projection; adjusting lower (2%) is more optimistic.
All projections in the calculator can be displayed in today's dollars (real, inflation-adjusted) or future dollars (nominal). The "today's dollars" view shows what your portfolio is actually worth in purchasing power — usually the more intuitive framing for long-range planning.