What this calculator does
FIRE stands for Financial Independence, Retire Early. The idea is simple: once your investment portfolio is large enough that its expected returns can cover your annual expenses indefinitely, you no longer need to work. This tool helps you put a specific number on that threshold — your FIRE number — and estimates how many years you are away from reaching it given your current savings trajectory.
Adjust the six sliders and the target number, retirement age, and year-by-year projection update in real time. Switch between Korean (KO) and English (EN) modes in the top-right corner; each uses currency units and amount ranges tuned for that market.
The math, in three lines
- FIRE target = Annual expenses ÷ Safe withdrawal rate. Default SWR is 4%, which matches the classic Trinity Study result.
- Annual growth = Assets × Return rate + Annual savings added at the end of each year.
- Retirement year = the first year where end-of-year assets reach the FIRE target. After that, savings stop and the portfolio continues to grow at the return rate.
How to use this tool
- Pick a language (KO or EN) — this also sets sensible slider ranges for the currency.
- Enter your current age and current invested assets.
- Set your annual savings — the money you expect to add to your portfolio every year.
- Set your annual expenses. This is what you expect to spend per year in retirement, in today’s money.
- Set an expected annual return rate. 6% real (after inflation) is a common long-horizon assumption for a diversified equity-heavy portfolio.
- Pick a safe withdrawal rate. 4% is the most common; more conservative investors use 3.5% or 3%.
- Read the four summary cards and the projection table to see your target, retirement age, and year-by-year growth.
Three profiles to try
Aggressive saver — high income, low expenses, high savings rate. Watch how pushing savings from $30K to $60K moves the retirement age forward by a decade or more. Savings rate is the single biggest lever you control.
Standard trajectory — default values. A 28-year-old with $300K invested, saving $50K a year at 6% real return and 4% SWR typically hits FIRE somewhere in their early-to-mid 50s.
Lean FIRE — very low expenses. Drop annual expenses and the FIRE target falls proportionally. For many people, cutting expenses by 20% pulls retirement in faster than a 20% raise would.
Limitations of this model
- Real markets do not deliver a constant return. Sequence-of-returns risk — getting a bad decade early in retirement — can meaningfully change the safe withdrawal rate.
- Taxes are not modeled. Retirement-account structure (401k, IRA, ISA, 연금저축) will change effective take-home numbers.
- Healthcare and long-term care costs vary enormously by country and are not separately modeled.
- Income growth over your career is not modeled — actual savings will probably rise over time.
Use this as a starting point for thinking about your trajectory, not as a definitive plan. For a real plan, pair it with a licensed financial advisor in your jurisdiction.
Frequently asked questions
What is a FIRE number?
Your FIRE number is the amount of invested assets you need before you can retire. The classic rule of thumb takes your expected annual expenses in retirement and divides by a safe withdrawal rate (SWR) — typically 4%. So if you expect to spend $50,000 a year, your FIRE number is $50,000 ÷ 0.04 = $1,250,000.
Why 4%?
The 4% rule comes from the Trinity Study, which back-tested 30-year retirement portfolios of stocks and bonds against historical US market returns. A 4% initial withdrawal rate, adjusted for inflation each year, survived nearly all 30-year periods. It is a rule of thumb, not a guarantee — longer retirements or less diversified portfolios may warrant a lower SWR.
What assumptions does the calculator make?
A constant annual real return rate (your input), constant annual savings until retirement, constant annual expenses, and that investment returns compound yearly. It does not model inflation directly — if you enter numbers in today's dollars and a real return rate, the result is approximately inflation-adjusted.
Why do my numbers look impossible to reach?
The three biggest levers are savings rate, expenses, and return. Try lowering your annual expenses (which also lowers the target itself), raising your annual savings, or revisiting whether your return-rate assumption is realistic. Small changes compound over decades.
Is my financial data uploaded anywhere?
No. All calculations run in your browser. Nothing you type is sent to a server, stored, or logged.
Why is there both a Korean and English mode?
Korean and US personal-finance conversations use different currencies and very different typical amounts. The KO mode uses 만원 (10,000-won units) with ranges tuned for Korean savings patterns; the EN mode uses US dollars with ranges tuned for a US income profile. The underlying math is identical.
Related reading
- What Is Your FIRE Number? How to Calculate Financial Independence — a longer walkthrough of the 4% rule, withdrawal-rate research, and how savings rate dominates every other variable.