FIRE Calculator
Financial Independence, Retire Early — find your FIRE number and timeline
What is the FIRE Calculator?
FIRE stands for Financial Independence, Retire Early. The idea is to save and invest aggressively enough that your investment portfolio generates enough passive income to cover your living expenses indefinitely, and you never have to work again unless you want to. The FIRE Calculator tells you your target portfolio size, how long it will take you to get there, and whether your current savings rate is enough to hit it. It's widely used in communities like r/financialindependence, and by people who are serious about leaving the traditional work timeline behind. Vanguard and Fidelity index fund investors are the typical users.
How Does It Work?
The FIRE number is based on the 4% rule, a guideline from the Trinity Study suggesting you can safely withdraw 4% of your portfolio annually without running out of money over a 30-year retirement.
FIRE Number = Annual Expenses ÷ 0.04 (i.e., Annual Expenses × 25)
Years to FIRE = based on current savings, annual contributions, and expected investment returns (typically 7% nominal, 5% real). Annual Expenses is what you currently spend or expect to spend in retirement. Current Portfolio Value is your total invested assets today. Annual Savings is how much you add per year. Expected Return is your assumed growth rate.
How to Use CalciHub's FIRE Calculator
1. Enter your current annual expenses (what you actually spend per year).
2. Adjust for expected retirement expenses if different.
3. Enter your current investment portfolio value.
4. Add your annual savings and investment contribution amount.
5. Set your expected annual return rate (7% is common for a diversified equity portfolio).
6. Tip: Run two scenarios: one with your current expenses, one with reduced retirement expenses. Many FIRE planners find cutting $10,000/year from their annual spend shaves years off their timeline.
A Quick Example
David, 32, lives in Portland and spends $52,000 a year. His FIRE number: $52,000 × 25 = $1,300,000.
He has $180,000 invested across a 401k and a Vanguard brokerage account. He saves $30,000 per year. Assuming 7% annual returns, the calculator estimates he reaches $1.3M in approximately 19 years, retiring at 51.
If David trims his annual spending to $44,000, his FIRE number drops to $1,100,000 and his timeline shortens to about 16 years. Three years of extra freedom in exchange for lifestyle adjustments.
Frequently Asked Questions
The 4% rule comes from the 1994 Trinity Study, which found that a portfolio of 50–75% stocks could sustain 4% annual withdrawals for at least 30 years across historical market conditions. More recent research by financial planners like Big ERN has suggested 3.5% may be safer for very long retirements (40+ years). It's a useful starting point, not a guarantee.
Savings rate is the most powerful lever in the FIRE equation. Saving 10% of your income puts retirement 40+ years out. Saving 50% gets you there in roughly 17 years. Saving 70–75% can get you there in under 10 years. This math, popularised by Mr Money Moustache, is based on standard compound growth assumptions.
LeanFIRE targets a minimal retirement budget — typically under $40,000/year for a single person. Regular FIRE aims for moderate spending around the US median. FatFIRE targets a comfortable retirement with $100,000/year or more in spending. All three use the same 4% rule math; they just start from different annual expense targets.
If you're retiring in your 40s or early 50s, Social Security is decades away — so most FIRE planners exclude it from their core calculation and treat it as a cushion. If you're targeting a more traditional early retirement in your mid-50s, it's reasonable to include a partial Social Security estimate from your SSA.gov statement.
Yes, completely free. No login needed. CalciHub's FIRE Calculator is available at calcihub.com at zero cost whenever you want to run your numbers.
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