Scenario
What happens if inflation averages 4 percent?
Last updated: October 2026
Specific retirement question
This scenario compares a higher inflation setting with other assumptions kept close. The key question is how quickly purchasing power erosion can shorten success odds in early and mid-retirement years.
It is an educational simulation. The output does not guarantee a result and does not replace personalized planning.
Inputs used
- Current age 40
- Target retirement age 57
- Current savings $500,000
- Monthly contribution $2,000
- Expected return 7.0%
- Inflation 4.0%
- Annual spending $65,000 in today’s dollars
- Withdrawal rate 3.5%
- Volatility 17%
Result summary
Estimated FIRE number: about $1,860,000 in today's dollars ($65,000 ÷ 3.5%). At 4% inflation the calculator inflates this to about $3,620,000 in age-57 dollars.
Projected portfolio: around $2,320,000 at age 57 in deterministic modeling, about $1,300,000 short of the inflated FIRE number.
Safe withdrawal amount: roughly $81,000 per year in age-57 dollars (3.5% of the projected portfolio).
Success rate: around 30% in this inflation-stress setup, versus about 45% with the same inputs at 3% inflation.
Tradeoff analysis
- Higher inflation target: pushes spending to rise faster than nominal growth alone.
- Portfolio durability: a portfolio that appears sufficient in nominal terms may be insufficient in real terms.
- Spending categories: discretionary categories often absorb shocks unevenly, so category-level planning helps.
- Timing flexibility: the value of optional spending cuts increases when inflation is high.
Monte Carlo interpretation
A 30% success rate means only about 300 of 1,000 simulated paths survived this inflation stress profile. This signals that sequence plus inflation can dominate a simple average-return lens.
Use this result to compare against your preferred spending flexibility, especially in the first 10 years of retirement.
Sensitivity notes
- At 3% inflation, the inflated FIRE number falls to about $3,070,000 for the same lifestyle.
- At 4.5% inflation, success falls to about 23% unless spending can flex.
- An 8% return assumption lifts success to about 44%, which still does not offset the inflation drag.
- Retiring two years later, at 59, lifts success to about 36%.
Common mistakes
- Assuming historical average inflation will persist without testing a higher setting.
- Treating category spending as fixed and not adaptable under inflation pressure.
- Using the deterministic FIRE number without reviewing simulation spread.
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