Inflation Impact on Your FIRE Number

Inflation Impact on Your FIRE Number

Inflation is the silent wealth eroder. It doesn't show up as a line item on your statement, but it steadily reduces what your money can buy. For FIRE planning, where you're projecting expenses decades into the future, getting inflation assumptions right is critical.

The Current Inflation Landscape

As of December 2025, the annual US inflation rate was 2.7%, with core inflation (excluding food and energy) at 2.6%. This is close to the Federal Reserve's 2% target but above it. The previous few years saw inflation spike significantly before moderating, reminding everyone that inflation isn't always predictable.

For long-term planning, the question isn't today's inflation rate but what inflation might average over your retirement horizon. Historical US inflation has averaged around 3% over the past century, with significant variation including both low-inflation decades and high-inflation periods.

Real vs. Nominal Returns

When thinking about FIRE, always work in real (inflation-adjusted) terms. A portfolio returning 8% nominally with 3% inflation gives you 5% real return. That 5% is your actual purchasing power growth. The standard FIRE planning approach uses real return assumptions specifically because they account for inflation automatically.

The classic 4% withdrawal rule is expressed in real terms: withdraw 4% in year one, then adjust that dollar amount for inflation each year. Your withdrawals grow with inflation to maintain purchasing power.

Healthcare Inflation Deserves Special Attention

General inflation statistics mask significant variation by category. Healthcare costs have historically grown faster than general inflation, often 5-6% annually. If you're planning for early retirement without employer-subsidized health insurance, you might want to budget healthcare costs separately with a higher inflation assumption.

How to Handle Inflation in Your Planning

Most FIRE calculators work in real terms, meaning the returns you input should already be inflation-adjusted. If you're using 7% as your expected return, that should represent real returns. Your expense estimates should be in today's dollars, and the calculator handles inflation implicitly.

If you're building your own projections, explicitly model inflation. Start with today's expenses, grow them at your assumed inflation rate, and ensure your portfolio growth assumptions are also inflation-adjusted.

Protecting Against Inflation Surprises

Inflation assumptions are just that: assumptions. To protect against higher-than-expected inflation, consider TIPS (Treasury Inflation-Protected Securities) for a portion of your portfolio, as they're indexed to CPI. I Bonds offer inflation protection for smaller amounts. Real estate and equities have historically provided some inflation protection over long periods.

The ultimate protection is flexibility. If inflation runs hot, having the ability to reduce discretionary spending, earn supplemental income, or adjust your lifestyle provides real options that rigid calculations can't.

Inflation isn't dramatic, but it's relentless. Plan for it explicitly rather than hoping it stays low.