Find your FIRE number and how many years until you could retire early — based on your income, expenses, savings, and expected return. Free, no signup.
Your FIRE number (portfolio needed)
$1,000,000
Years to FIRE
14
Age at FIRE
44
You save / year
$40,000
Savings rate
50%
Estimates only, in today's dollars. Assumes constant return and contributions and ignores taxes and inflation adjustments.
Retirement income from a portfolio is whatever you can withdraw each year without draining it. That makes it a single multiplication: the balance you retire with, times the withdrawal rate you consider safe.
Annual Retirement Income = Portfolio Value × Safe Withdrawal Rate
Run it backwards and you get the target the calculator above solves for — the portfolio that supports the spending you actually have:
FIRE Number = Annual Expenses ÷ Safe Withdrawal Rate
Take a $900,000 portfolio and the classic 4% withdrawal rate.
In the other direction, someone who spends $60,000 a year needs $60,000 ÷ 0.04 = $1,500,000 — the familiar 25× rule, since dividing by 0.04 is the same as multiplying by 25. Choosing a more cautious 3.5% rate raises that target to $60,000 ÷ 0.035 = $1,714,000. If a pension or Social Security will cover $20,000 of that spending, subtract it first: only $40,000 ÷ 0.04 = $1,000,000 has to come from the portfolio.
The gap between what you earn and what you spend, invested consistently, does nearly all the work. That gap has a name and a formula:
Savings Rate = (Income − Expenses) ÷ Income × 100
Project it forward the same way the calculator does — existing savings compounding, plus each year's contributions compounding for the years they have left:
Future Value = Savings × (1 + r)^n + Annual Contribution × [((1 + r)^n − 1) ÷ r]
Someone earning $80,000 and spending $52,000, with $100,000 already invested and a 6% expected return after inflation:
Now notice what cutting spending does. Trimming $200 a month is $2,400 a year: it lifts annual savings to $30,400 and drops the target by $2,400 × 25 = $60,000, to $1,240,000. The two ends move toward each other, which is why expense cuts shorten the timeline far more than an equivalent raise.
The years-to-FIRE figure is a planning estimate, not a date. Real returns arrive unevenly, and retiring into a bad first few years is the main risk a 4% withdrawal rate is meant to survive — which is why 3–3.5% is common for anyone planning a retirement longer than 30 years. Treat the income figure as pre-tax: withdrawals from a traditional 401(k) or IRA are taxed as ordinary income, while a Roth is not, so the same balance can support meaningfully different spending. And check what your number is measured in — if you use a nominal return, the target needs inflating too; using a real (after-inflation) return, as in the example above, keeps everything in today's dollars.
Your FIRE number is the portfolio size that lets you live off withdrawals indefinitely. It equals your annual expenses divided by your safe withdrawal rate — at the common 4% rate, that is 25× your annual expenses.
The percentage of your portfolio you can withdraw each year with low risk of running out. The classic figure is 4% (the "4% rule"), though some prefer 3–3.5% for a longer or more conservative retirement.
We compound your current savings plus your annual contributions (income minus expenses) at your expected return until the balance reaches your FIRE number. A higher savings rate shortens the timeline far more than a higher return.
Coast FIRE is when your existing investments will grow to your FIRE number by retirement age without any further contributions — so you only need to cover current expenses. Increase the age gap and set contributions low to approximate it here.
Multiply the portfolio you expect to retire with by your safe withdrawal rate: retirement income = portfolio value × withdrawal rate. A $900,000 portfolio at 4% supports $36,000 a year, or $3,000 a month, before tax. Add any pension and Social Security on top of that figure, and subtract them from your target first if you want to know how much the portfolio alone has to cover.
Almost all of it comes from your savings rate and time invested rather than picking winners. Save a consistent percentage of income into low-cost, broadly diversified funds, capture every dollar of employer match, keep the money invested through downturns, and let each raise increase the amount saved rather than the amount spent. Cutting a recurring expense does double duty: it frees cash to invest and permanently lowers the portfolio you need, since your target is roughly 25× annual spending.
A 4% rule calculator answers two related questions: how much you can safely withdraw each year from a given portfolio (portfolio × 4%), and how large a portfolio you need to support a given spending level (annual expenses ÷ 4%, the same as 25× your expenses). The calculator above does both — enter your numbers to see your FIRE number and safe annual withdrawal at the 4% rate, or adjust the withdrawal rate to see how a more conservative 3–3.5% changes the target.
Keep going
See how reinvested dividends accelerate your path with the DRIP calculator, or model raw growth with compound interest.