FIRE Calculator
FIRE stands for Financial Independence, Retire Early: building a portfolio large enough that its returns cover your spending, so work becomes optional. The core of it is one number — your FIRE number — which is your yearly spending divided by a safe withdrawal rate. This calculator finds that number, then simulates how long it takes to reach it from your current savings and savings rate, using real (after-inflation) returns so that everything stays in today’s money. It also shows your Coast FIRE number: the amount you would need invested right now so that, with no further contributions, growth alone carries you to a traditional retirement.
How to use the fire calculator
- Enter your expected yearly spending in retirement — the number that matters most.
- Enter your current invested savings and how much you add each year.
- Choose a return, inflation and withdrawal rate. If you are unsure, use 7%, 2% and 4%, then test cautious values such as 5%, 3% and 3.5%.
- Read your FIRE number and time to reach it, and check your Coast FIRE figure for a lower-pressure milestone.
Formula
FIRE number = yearly spending ÷ withdrawal rate (4% means 25 × spending). Growth is modelled in real terms: real return = (1 + return) ÷ (1 + inflation) − 1. Each month the balance grows by the monthly real return and one-twelfth of your yearly saving is added, until it reaches the FIRE number. Coast FIRE number = FIRE number ÷ (1 + real return)years to traditional retirement.
Worked examples
Spending $40,000 a year
Spending $40,000 a year at a 4% withdrawal rate means a FIRE number of $1,000,000.00 (25× spending). Starting with $100,000 and saving $30,000 a year at a 7% return and 2% inflation, you reach it in about 16 years, 11 months.
The power of the savings rate
Raising yearly saving from $30,000 to $45,000 on the same plan shortens the time to 13 years, 1 month. Savings rate matters more than return because it both raises contributions and lowers the spending you need to replace.
Coast FIRE
With 25 years to a traditional retirement age, your Coast FIRE number is $302,280.31 (grows to your FIRE number in 25 years with no more saving). If you already have that much invested, you could cover only your current living costs from work and let the portfolio compound the rest of the way.
FIRE variants and withdrawal rates
Common flavours
| Style | Idea |
|---|---|
| Lean FIRE | Retire on a modest budget, with a smaller FIRE number |
| Fat FIRE | Retire with a generous budget — a much larger number |
| Coast FIRE | Invest enough early that growth alone reaches the target; only cover current expenses |
| Barista FIRE | Part-time work covers some costs so the portfolio can be smaller |
Withdrawal rate and the FIRE number
| Withdrawal rate | FIRE number for $40,000 spending |
|---|---|
| 3% | $1,333,333.33 |
| 3.5% | $1,142,857.14 |
| 4% | $1,000,000.00 |
| 5% | $800,000.00 |
Lower withdrawal rates are safer for long retirements but demand a larger portfolio. Compare with a traditional plan on the retirement calculator.
Practice problems
Try these yourself first, then check your answer. The answers come from the calculator above.
- Spending $50,000 a year, with $150,000 saved, saving $40,000 a year at 7% and 2% inflation. What is the FIRE number and how long to reach it?
Show answer
Your FIRE number: $1,250,000.00 · Time to reach it: 15 years, 9 months
Common mistakes to avoid
- Using a 4% rate for a 50-year retirement. The classic studies covered about 30 years; early retirees often choose 3–3.5%.
- Forgetting healthcare costs, especially in countries without universal coverage, and taxes on withdrawals.
- Counting a home you live in as part of the FIRE number. Only investments that can fund spending count.
- Assuming returns arrive smoothly. A bad market early in retirement does the most damage (sequence-of-returns risk).
- Ignoring spending changes. Costs often fall in some categories and rise in others (healthcare, travel) over decades.
Frequently asked questions
What is a FIRE number?
The portfolio size at which a safe withdrawal rate covers your yearly spending: spending ÷ withdrawal rate. At 4% it is 25 times your annual spending.
How long does it take to reach FIRE?
It depends mostly on your savings rate. The calculator simulates it from your numbers — try changing the yearly saving to see the effect.
What is Coast FIRE?
The amount invested today that will grow to your full FIRE number by a traditional retirement age with no further contributions, letting you ease off saving.
Is the 4% rule safe for early retirement?
It is based on 30-year US market history. For retirements of 40–50 years many people use 3–3.5% for a margin of safety.
Why does the calculator use real returns?
So the answer is in today’s money. Spending today and spending in 20 years are only comparable once inflation is stripped out.
Is this financial advice?
No. It is an educational model. Markets, taxes and life change, so review your plan regularly with a qualified adviser.
Sources and further reading
By Thomas M, Registered Investment Adviser (South Carolina), who launched his own financial advisory firm in 2010. Last reviewed September 26, 2026. Found a mistake? Tell us; see our editorial policy.