Retirement Calculators
FIRE & Coast FIRE Calculator
A financial independence retire early calculator that shows your full FIRE number, your Coast FIRE number, and how many years away you are from each — with a sensitivity table for the ongoing 4% vs. 3.25% withdrawal-rate debate.
Calculate your FIRE and Coast FIRE numbers
Your FIRE number at different withdrawal-rate assumptions
| Withdrawal rate | FIRE number |
|---|
Assumes a constant, smooth rate of return — real markets don’t move smoothly, and sequence-of-returns risk (bad years early in retirement) matters more than the average. Nominal figures, not inflation-adjusted.
The math behind FIRE
Two formulas, both older and simpler than they look.
FIRE number
Your annual spending, divided by your withdrawal rate — same as multiplying by 25 at the traditional 4% rate.
expenses ÷ withdrawal rate
Coast FIRE number
The present value of your FIRE number — how much, invested today, grows to that target with zero more contributions.
FIRE number ÷ (1 + return)^years
Years to FIRE
Your current savings, compounding and growing by your annual contribution, until it crosses your FIRE number.
simulated year by year
What FIRE actually means
FIRE — Financial Independence, Retire Early — is a savings framework, not a specific age or number. A financial independence retire early calculator exists to answer one question: how much invested money do you need before work becomes optional? The math behind it is decades old — economist and financial planner William Bengen published the underlying withdrawal-rate research in 1994, and three professors at Trinity University stress-tested it against historical market data in 1998. The “FIRE” branding and online movement came later, popularized in the 2010s, but the arithmetic hasn’t changed.
The 25x rule and the 4% rule are the same idea
If you can safely withdraw 4% of your portfolio each year, then your portfolio needs to be 25 times your annual spending — 1 ÷ 0.04 = 25. A retirement calculator fire tool that asks for your annual expenses and gives you a target number is just running that division. Someone spending $50,000 a year needs $1,250,000 invested at the traditional 4% rate.
Is 4% still the right number for FIRE specifically?
This is genuinely contested, and it matters more for FIRE than for traditional retirement. The 1998 Trinity Study tested withdrawal rates against historical 30-year periods — the standard length of a retirement starting at 65. But FIRE retirees who stop working at 35 or 45 need their money to last 50 or 60 years, not 30. Over that much longer horizon, a growing number of researchers and FIRE educators now argue for a more conservative 3.25–3.5% withdrawal rate instead of 4%, since a longer payout period gives market downturns more time to do damage.
What Coast FIRE means, and how it’s different
A coast fire retirement calculator answers a different question than a standard FIRE calculator: not “when can I stop working entirely,” but “when have I saved enough that I never have to save for retirement again?” Once your current invested balance is large enough that compound growth alone — with zero further contributions — will carry it to your full FIRE number by your target retirement age, you’ve hit Coast FIRE. From that point on, you only need to earn enough to cover today’s living expenses; retirement is already funded by money you’ve already saved.
This is why Coast FIRE is often reached years before full FIRE: it doesn’t require you to have your entire number today, just enough that time and growth do the rest of the work.
FIRE variants: Lean, Fat, Barista, and Coast
| Variant | What changes |
|---|---|
| Lean FIRE | A minimal-spending target, producing a smaller FIRE number |
| Fat FIRE | A higher, more comfortable spending target — a larger FIRE number |
| Barista FIRE | Part-time work (often for health insurance) covers part of expenses, reducing withdrawal needs |
| Coast FIRE | Stop contributing to retirement once compound growth alone reaches your number by target age |
All of them use the same underlying 25x/4% math — a financial independence early retirement calculator for any variant just changes the expense assumption or adds a part-time income offset on top of the same core formula.
The practical hurdle FIRE calculators don’t show: healthcare
Retiring before 65 means retiring before Medicare eligibility. Most early retirees bridge the gap through ACA marketplace plans (premiums are income-based, which can work in your favor at a low withdrawal income), COBRA continuation of a former employer’s plan, or Barista FIRE-style part-time work that includes benefits. None of this changes the FIRE math above, but it’s a real cost that belongs in your annual expenses figure — don’t leave it out.
The 4%/25x framework traces to William Bengen’s 1994 withdrawal-rate research and the 1998 Trinity Study; the Coast FIRE present-value formula is standard compound-interest math used across the FIRE community. This is a planning tool, not investment or retirement advice — consult a qualified financial planner before making irreversible decisions like leaving a job.
Frequently asked questions
What people ask before trusting a FIRE number.
What is the FIRE number formula?
FIRE number = annual expenses ÷ withdrawal rate. At the traditional 4% rate, that’s the same as annual expenses × 25. Spending $60,000/year means a $1.5 million FIRE number at 4%.
What is a good Coast FIRE number?
There’s no universal “good” number — it depends entirely on your current age, target retirement age, and expected return. The further away your target retirement age, the smaller your Coast FIRE number will be, since compound growth has more years to work.
Should I use 4% or 3.5% for my FIRE calculation?
4% remains the most commonly cited figure and is a reasonable starting point, but it was tested against 30-year retirement periods. If you’re planning a 40-60 year retirement, many FIRE researchers now suggest 3.25-3.5% is more conservative and appropriate — use the sensitivity table above to see both.
Once I hit Coast FIRE, do I have to stop contributing entirely?
No — Coast FIRE means you no longer need to contribute to hit your number by your target age, not that you’re prohibited from doing so. Many people keep contributing at a reduced rate for extra safety margin or to retire sooner than originally planned.
Does this calculator account for taxes and healthcare costs?
Not directly — you should build your best estimate of healthcare premiums and taxes into the “annual expenses” figure you enter, since both are real costs that affect how large your FIRE number needs to be.