FIRE Calculator
Find your financial independence number and how many years until you reach it, modeled in today's dollars using the 4% rule.
Assumptions
- Everything is modeled in today's dollars (real terms). The return you enter is already after inflation, so the FIRE number and the years to reach it are in today's purchasing power, not a nominal future projection.
- The FIRE number is your annual expenses divided by your withdrawal rate, the inverse of the 4 percent rule (a 4 percent rate gives 25 times your annual expenses). The withdrawal rate is the share of your portfolio you assume you can spend each year without running out.
- Annual savings are your income minus your expenses, your savings rate is that amount as a percent of income, and your age at FIRE is your current age plus the years to FIRE.
- Annual savings are held constant in real terms and invested at the real return at the end of each year, while your current savings compound at the same return. Because many people save more as income outpaces expenses over a career, the real-world timeline is often shorter than shown, so the calculator is conservative on timing.
- Years to FIRE is the first year your projected real-terms balance reaches or exceeds the FIRE number. It is 0 if your current savings already meet the number, and it is blank if the balance never reaches it within the search horizon of 80 years. The balance is projected even when your savings are zero or negative, because your existing portfolio keeps compounding, so it can still cross the target.
- The 4 percent rule is a guideline drawn from historical U.S. returns over a roughly 30-year retirement, not a guarantee. Its main risk is sequence-of-returns risk: poor returns early in retirement can drain a portfolio even when long-run averages are fine, and longer early-retirement horizons often use a lower rate, such as 3.5 percent.
- Not modeled: taxes, Social Security or other income, healthcare cost changes, one-time expenses, and any variation in your return, income, or spending over time.
- Results are rounded to the nearest cent, with years to FIRE and age shown as whole numbers. This is an estimate for educational purposes only, not financial, legal, or tax advice. Consult a qualified professional for guidance specific to your situation.
How it works
FIRE, financial independence and retiring early, means having enough invested that your portfolio can cover your spending indefinitely. Two numbers matter: how much you need, and how long until you have it.
Your FIRE number is your annual expenses divided by a safe withdrawal rate:
FIRE number = annual expenses / withdrawal rate
At the common 4% rate, that is 25 times your annual expenses. We then project your savings forward each year, adding what you save and growing it at your expected return, until the balance reaches the FIRE number. That year is your years to FIRE, and your current age plus that is your age at FIRE.
In today’s dollars (real terms)
This calculator works entirely in today’s dollars. The return you enter is a real return, meaning after inflation, so your FIRE number and the years to reach it are in today’s purchasing power. That avoids guessing what a future dollar will buy. A common long-run real return estimate for a diversified portfolio is around 5%.
Worked example
Age 35, $50,000 saved, $80,000 income, $50,000 expenses, 5% real return, 4% withdrawal rate:
- FIRE number =
$50,000 / 0.04 = $1,250,000. - You save
$80,000 − $50,000 = $30,000a year, a 37.5% savings rate. - Projecting forward, your balance reaches $1,210,875.68 after 21 years and $1,301,419.47 after 22 years, so you cross the FIRE number in year 22, at age 57.
Which way is the thumb on the scale?
This model holds your savings constant in real terms. In practice, most people’s expenses rise more slowly than their income, so their savings rate climbs over a career. Because we do not model that, the real-world time to FIRE is usually shorter than shown here. In other words, the calculator is conservative on the timeline: if anything, you are likely to get there sooner. Modeling a rising savings rate is a planned enhancement.
The 4% rule and its limits
The 4% rule comes from the Trinity study, which looked at U.S. historical returns and found that withdrawing 4% of a starting portfolio, adjusted for inflation, rarely exhausted it over 30 years. It is a useful guideline, not a guarantee. The main risk is sequence-of-returns risk: poor returns early in retirement can permanently shrink a portfolio even when long-run averages are fine. Early retirees with horizons longer than 30 years often plan for a lower rate, such as 3.5%. This is an estimate for planning, not financial advice.
Sources
- Cooley, Hubbard, and Walz, the Trinity study on sustainable withdrawal rates.
- Standard future-value-of-an-annuity math, applied in real (inflation-adjusted) terms.
Frequently asked questions
- What is the 4% rule and where does it come from?
- The 4% rule comes from the Trinity study, which found that retirees who withdrew 4% of their starting portfolio (adjusted for inflation) rarely ran out of money over 30 years in U.S. historical data. It implies a FIRE number of 25 times your annual expenses. It is a guideline based on the past, not a guarantee.
- What are the risks of the 4% rule?
- The biggest is sequence-of-returns risk: a bad market early in retirement can permanently shrink a portfolio even if average returns are fine. The rule also assumes a roughly 30-year horizon and historical returns. Early retirees with longer horizons often plan for a lower rate, such as 3.5%.
- Why is this in today's dollars?
- FIRE planning is clearest in real terms. By using a return after inflation, the FIRE number and the years to reach it stay in today's purchasing power, so you do not have to guess what a future dollar will buy.
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Last reviewed June 2026. For education, not financial advice.