Financial Independence Calculator
✦ Finance & MoneyUse this FIRE calculator to turn your savings rate into a FI number and years to financial independence, then see what a Coast FI balance would be.
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- ✓ Nothing you type is stored
- ✓ No sign-up required
- ✓ Formula and sources shown
The formula
FI number and months to financial independence
T = \frac{S}{w}, \qquad n = \frac{\ln\left(\dfrac{T + p/i}{P + p/i}\right)}{\ln(1 + i)}, \qquad C = \frac{T}{(1 + i)^{12y}}S is annual spending (take-home income × (1 − savings rate)), w the withdrawal rate, T the FI number, P your net worth, p the monthly saving, i the monthly return (annual ÷ 12) and n the months until your balance reaches T. C is the Coast FI number: the balance that grows to T in y years with no more saving. Months round up.
Calculating it by hand
- Enter your take-home (after-tax) annual income and the share of it you save; the rest is your annual spending.
- Divide that spending by your withdrawal rate to get the FI number. At 4% this is spending × 25.
- Enter your current net worth and an expected real (after-inflation) annual return.
- Solve for the months until your net worth plus level monthly saving reaches the FI number, and divide by 12 for years.
- For Coast FI, discount the FI number back from your chosen Coast age at the same return; that is the balance needed today.
- Change the savings rate, or the spending level behind Lean, Fat and Barista FI, and compare the years each takes.
Worked examples
Starting from $0 at a 50% savings rate
Age 30, net worth $0, take-home income $100,000, savings rate 50%, real return 5%, withdrawal rate 4%.Annual spending = $100,000 × (1 − 0.50) = $50,000, so the FI number = $50,000 ÷ 0.04 = $1,250,000.Monthly saving = $50,000 ÷ 12 = $4,167. With i = 0.05 ÷ 12, n = ln[(1,250,000 + 1,000,000) ÷ (0 + 1,000,000)] ÷ ln(1.0041667) ≈ 195.03, rounded up to 196 months.196 months = 16 years 4 months. Coast FI at age 65 (35 years out) = $1,250,000 ÷ (1 + 0.05 ÷ 12)^420 = $218,009.
FI number $1,250,000, reached in 196 months (about 16.3 years). Coast FI number at 65 is $218,009.
A higher spending target with part-time income
Age 40, net worth $200,000, take-home income $90,000, savings rate 35%, return 5%, withdrawal rate 3.5%, Coast age 60, part-time income $20,000.Annual spending = $90,000 × 0.65 = $58,500, so the FI number = $58,500 ÷ 0.035 = $1,671,429. Monthly saving = $31,500 ÷ 12 = $2,625.n = ln[(1,671,429 + 630,000) ÷ (200,000 + 630,000)] ÷ ln(1.0041667) ≈ 245.3, rounded up to 246 months (20 years 6 months).Barista FI: ($58,500 − $20,000) ÷ 0.035 = $1,100,000, reached in 177 months (14 years 9 months). Coast FI at 60: $1,671,429 ÷ (1.0041667)^240 = $616,163.
FI number $1,671,429 in 246 months (20.5 years). Barista FI target $1,100,000 in 177 months. Coast FI at 60 is $616,163.
Starting later with a head start
Age 45, net worth $400,000, take-home income $80,000, savings rate 30%, return 5%, withdrawal rate 4%, Coast age 60.Annual spending = $80,000 × 0.70 = $56,000, so the FI number = $56,000 ÷ 0.04 = $1,400,000. Monthly saving = $24,000 ÷ 12 = $2,000.n = ln[(1,400,000 + 480,000) ÷ (400,000 + 480,000)] ÷ ln(1.0041667) ≈ 182.6, rounded up to 183 months (15 years 3 months), so FI arrives at age 60.Coast FI at 60 (15 years out): $1,400,000 ÷ (1.0041667)^180 = $662,344. Net worth of $400,000 is below that, so it does not yet cover Coast FI.
FI number $1,400,000 in 183 months (15 years 3 months), at age 60. Coast FI number at 60 is $662,344.
Methodology
How your savings rate sets your FI date
Financial independence is a ratio, not a salary: how much you spend sets the target, and how much you keep sets the pace. Most people overlook that a higher savings rate shortens the date twice, by building the balance faster and by lowering the target.
Read sources and limitsWhat is a FIRE number?
A FIRE number, also called a FI number, is the invested balance at which a chosen share of it can cover your yearly spending. The rule is spending ÷ withdrawal rate. At a 4% withdrawal rate, which is the same as multiplying spending by 25, spending of $36,000 a year gives a FI number of $900,000.
At 3.5% the same spending needs $1,028,571, and at 3% it needs $1,200,000.
The number depends on spending, not income. A household earning $60,000 and spending $36,000 needs the same $900,000 as one earning $200,000 and spending the same $36,000. The 4% figure is a community shorthand drawn from historical research on 30-year withdrawals; it is a starting convention, not a guarantee, and this page lets you change it.
Why does savings rate matter more than income?
Your savings rate drives both halves of the calculation. Saving more adds to the balance each month, and spending less lowers the FI number you are aiming at. Starting from $0, with take-home income of $60,000, a 5% real return and a 4% withdrawal rate, a 10% savings rate takes 50.3 years.
A 20% rate takes 35.9 years, 50% takes 16.3 years and 80% takes 5.5 years.
The curve flattens at the low end and falls steeply in the middle, which is why moving from 10% to 20% saves about 14 years while moving from 50% to 60% saves about 4. The chart on this page plots the curve for your own income, return and withdrawal rate, once from your current net worth and once from $0 so you can see what your starting balance is worth.
What are Coast, Lean, Fat and Barista FI?
These are community labels, not official standards. Coast FI is the balance that would grow to your FI number by a traditional age with no further saving. At the defaults, with age 65 as the target, it is $156,966 today.
Lean FI uses a lower spending level, here 70% of your current spending, so the target falls to $630,000 and the date to 14 years and 10 months. Fat FI uses 150%, a $1,350,000 target and 24 years and 11 months.
Barista FI assumes part-time income covers some of your spending, so the portfolio only has to cover the gap. With $12,000 a year of part-time income against $36,000 of spending, the target drops to $600,000 and the date to 14 years and 4 months. The Lean and Fat percentages and the Coast age are yours to change under Advanced.
How does the calculator solve for the date?
It treats your savings as a level monthly deposit made at the end of each month and your balance as growing at the return you enter, compounded monthly. The months until the balance reaches the FI number come from the closed-form annuity equation shown in the formula section, and the result is rounded up to a whole month.
At the defaults that is 231 months, or 19 years and 3 months, which puts you at age 49.
A higher return helps but less than most expect: 4% gives 21 years, 5% gives 19.3 and 6% gives 17.8. Inflation and fees are optional. A 7% return with 2.5% inflation and a 0.5% fee works out to about 3.9% in real terms and 254 months. If the return is zero, the answer is simply the shortfall divided by what you save; with no saving and no growth it never arrives.
Is the 4% rule enough for FIRE?
The 4% rule comes from studies of United States market history, notably William Bengen in 1994 and the Trinity study in 1998, which tested 30-year retirements. Someone retiring in their thirties or forties may need the money to last 50 years or more, which is why many early-retirement writers test 3% to 3.5%.
The calculator shows what each rate does to the target and the date so you can compare the trade-off yourself.
This is an illustration, not advice, and it does not say you are or are not financially independent. It assumes a constant return and steady spending, and it ignores taxes on withdrawals, healthcare costs before Medicare, Social Security and the order in which good and bad market years arrive. Treat the result as a way to compare scenarios, and use the plan documents from your own accounts for decisions.
Financial Independence questions
How much do I need for FIRE?
You need your annual spending divided by your withdrawal rate. At the common 4% rate that is 25 times your spending, so $36,000 a year needs $900,000 and $50,000 needs $1,250,000. At 3.5% the multiple is about 28.6 and at 3% it is 33.3. Spending, not income, sets the number, so cutting expenses lowers it directly.
What is a FIRE number?
A FIRE number, or FI number, is the invested balance at which your chosen withdrawal rate covers your yearly spending. It equals spending ÷ withdrawal rate: $40,000 a year at 4% gives $1,000,000. It is a convention taken from historical withdrawal research, not a guarantee, so many people test lower rates such as 3.5% for longer horizons.
What is Coast FI and how is it calculated?
Coast FI is the balance today that would grow to your FI number by a traditional retirement age with no more saving. It is the FI number discounted at your return for the years left. For a $900,000 target, 35 years and a 5% return it is $156,966. If your net worth is above it, the target can be reached by growth alone.
What savings rate do I need to reach FIRE?
It depends on how many years you will wait. Starting from $0 with take-home income of $60,000, a 5% real return and a 4% withdrawal rate, saving 20% takes about 35.9 years, 50% takes about 16.3 years and 75% takes 7 years. Starting with some net worth shortens each of these, and the chart shows your own curve.
What is Lean FIRE?
Lean FIRE means aiming for financial independence on a lower spending level than you live on today. This calculator treats it as a share of your current spending, 70% by default and editable. At $36,000 of spending that is $25,200 a year, a $630,000 target instead of $900,000, and it is reached about four and a half years sooner.
What is Barista FIRE?
Barista FIRE is a community term for stopping full-time work while part-time income covers part of your spending, so the portfolio only has to cover the difference. If you spend $36,000 and earn $12,000 part-time, the portfolio covers $24,000 and the 4% target is $600,000. You can enter your own part-time income under Advanced.
Is the 4% rule safe for FIRE?
The 4% figure comes from 30-year historical tests by Bengen (1994) and the Trinity study, and it carried no guarantee even there. A retirement that starts in your forties may last 50 years or more, which is why many people test 3% to 3.5%. At 3.5% the $900,000 target becomes $1,028,571 and at 3% it becomes $1,200,000.
How is the savings rate defined here?
Savings rate here is the amount you set aside divided by your take-home (after-tax) income, so a 40% rate on $60,000 means saving $24,000 and spending $36,000. Other sources divide by gross income or count an employer match differently, so the same person can report different rates. Use the definition you track, and be consistent.
What real return should I use?
Enter a return after inflation, because the target is in today's dollars; the default is 5% and it is only an illustration, not a forecast. Moving it matters: with the other defaults, 4% gives 21 years, 5% gives 19.3 and 6% gives 17.8. If you prefer a nominal return, use the Advanced fields for inflation and fees.
How is this different from the Early Retirement page?
Both ask when your savings can cover your spending, but this page starts from your savings rate and shows how the date changes as that rate moves from 5% to 80%, with Coast, Lean, Fat and Barista scenarios. The Early Retirement page on this site starts from a target age and works out the savings needed to reach it.
Source notes
Method, sources & limitations
Every figure on this page comes from the formula above applied to the values you enter. Nothing is estimated from market data, and no result is a forecast. These are the sources behind the method and any fixed figures it uses:
- Internal Revenue Service — Topic no. 558, Additional tax on early distributions from retirement plans
- Consumer Financial Protection Bureau — Plan for retirement
- Bengen (1994), Determining withdrawal rates using historical data, Journal of Financial Planning
- Cooley, Hubbard & Walz (1998), Retirement savings: choosing a withdrawal rate that is sustainable, AAII Journal
Educational information only. Results are estimates produced from the assumptions you enter, and are not financial, tax, legal or medical advice. Check anything that matters against a qualified professional and the cited sources.