FIRE stands for financial independence, retire early. The idea is simple: once your investments can cover your living costs indefinitely, work becomes optional. This FIRE calculator turns that into numbers. It shows how big your portfolio needs to be (your FI number), how many years of saving and compounding it takes to get there, and the smaller Coast FI amount after which growth alone finishes the job.
How to use the FIRE calculator
- Enter your expected yearly spending in retirement, in today’s dollars.
- Choose a safe withdrawal rate. 4% is the classic figure. Lower rates are more conservative.
- Enter how much you have invested so far and the amount you invest per year.
- Enter an expected return after inflation. Using a real return keeps everything in today’s dollars.
- Optionally add your age, your take-home pay to see your savings rate, and a traditional retirement age for the Coast FI target.
The FIRE formulas
With assets A, yearly investing S added at year-end and real return r, the years needed to reach the FI number are:
And the Coast FI amount, t years before your traditional retirement age:
Worked example
You are 32, plan to spend $50,000 a year and use a 4% withdrawal rate. You have $150,000 invested, add $36,000 a year out of $96,000 take-home pay (a 37.5% savings rate), and expect a 5% real return.
- FI number: $50,000 ÷ 0.04 = $1,250,000, or 25 times spending.
- Years to FI: ln[(1,250,000 × 0.05 + 36,000) ÷ (150,000 × 0.05 + 36,000)] ÷ ln(1.05) = ln(2.26437) ÷ 0.04879 = 16.75 years. You would reach FI at around 48 and a half.
- Coast FI for a retirement age of 60: $1,250,000 ÷ 1.0528 = $318,867. You are $168,867 away from the point where you could stop saving and still retire at 60.
Withdrawal rate changes the target
| Withdrawal rate | FI number | Time to FI from $150,000 |
|---|---|---|
| 3% | $1,666,667 | 20 years, 8 months |
| 3.5% | $1,428,571 | 18 years, 6 months |
| 4% | $1,250,000 | 16 years, 9 months |
| 4.5% | $1,111,111 | 15 years, 3 months |
| 5% | $1,000,000 | 14 years |
Savings rate changes everything
On $96,000 of take-home pay, spending whatever you don’t invest, at a 4% withdrawal rate:
| Savings rate | Time to FI |
|---|---|
| 10% | 39 years, 6 months |
| 30% | 23 years, 3 months |
| 50% | 13 years, 8 months |
| 70% | 6 years, 7 months |
A higher savings rate works twice. You invest more each year, and because you are living on less, the target itself shrinks.
Flavors of FIRE
- Lean FIRE: reaching independence on a frugal budget, often well under the national median spending.
- Fat FIRE: a larger target that supports generous spending, often 1.5 to 2 times typical expenses.
- Barista or Coast FIRE: reaching the Coast number, then working part-time or in a lower-stress job to cover current costs while the portfolio grows.
Before you quit your job
Early retirees need to plan for health insurance before Medicare starts at 65. They also need a way to reach retirement accounts before 59½ without the 10% additional tax, such as Roth contribution withdrawals, Roth conversion ladders or substantially equal periodic payments. Check how the money holds up through decades of withdrawals with the retirement withdrawal calculator, and model workplace savings with the 401(k) calculator.
Estimates only, not financial advice. Real returns vary year to year, and early retirement plans should allow for taxes, healthcare and spending flexibility.
Frequently asked questions
What is a FIRE number?
It is the invested balance that can fund your yearly spending indefinitely at a chosen withdrawal rate. Divide annual spending by the rate. At 4%, that means 25 times your spending: $50,000 a year needs $1,250,000.
Is 4% a safe withdrawal rate for early retirement?
The 4% guideline was tested over roughly 30-year retirements. Someone retiring at 40 may need the money to last 50 years or more, so many early retirees plan on 3.25% to 3.5%, or stay willing to cut spending in weak markets.
What is Coast FI?
Coast FI is the point where your current investments, left alone to grow, will reach your FI number by a traditional retirement age. After that you only need to earn enough to cover today's expenses. With a 5% real return and 28 years to go, a $1,250,000 target needs about $318,867 invested today.
Why use a return after inflation?
Using a real return keeps every number in today's dollars. Your spending, savings and FI number then stay comparable over decades without separate inflation adjustments. A 5% real return roughly matches a 7.5% nominal return with 2.5% inflation.
What matters most for reaching FI faster?
Your savings rate. Saving more speeds up the balance, and spending less also shrinks the FI number. At $96,000 of take-home pay, going from a 20% to a 50% savings rate cuts the time to FI from about 30 years to under 14 in this calculator.