FIRE / Coast FIRE Calculator

1. Enter your annual spending in retirement, in today's dollars, and any Social Security or pension you expect. Guaranteed income lowers what the portfolio must cover.
2. Add your current invested assets, your current age and your target retirement age.
3. Set the two assumptions: your safe withdrawal rate (example 4%) and your expected real return (example 5%). Both are your inputs, not promises.
4. Read your FIRE number, your Coast FIRE number today, whether you are already Coast FIRE, and the age you could stop contributing.

FIRE stands for financial independence, retire early. You reach financial independence when your invested money can cover your living costs without a paycheck. The target pile is your FIRE number.

The most common rule sets the FIRE number at your annual spending divided by a safe withdrawal rate. At a 4 percent rate that is 25 times your yearly spending, often called the 25x rule. The 4 percent figure comes from the Trinity study and William Bengen's 1994 research; it is a planning assumption, not a guarantee.

Coast FIRE is a milestone on the way. It is the smaller amount that, if you never add another dollar, still grows into your full FIRE number by your target retirement age. Once you hit it you can "coast": keep working to cover today's bills, but stop saving for retirement. For background on the movement and its variations, see what is the FIRE movement.

The tool uses two short formulas and no market forecasts. You supply the withdrawal rate and the real return, so the math stays honest and evergreen.

The real return is the return after inflation, which keeps every figure in today's dollars. The coast calculation is the same compounding used in our compound interest calculator, run in reverse to discount the FIRE number back to today.

1. Subtract any Social Security or pension from your spending to get what the portfolio must fund.
2. Divide that by your withdrawal rate to get the FIRE number.
3. Discount the FIRE number back over the years until retirement, at your real return, to get the coast number.
4. Compare your current assets with the coast number, and solve for the age your assets alone would reach the FIRE number.

The coast age uses logarithms: coast age = current age + ln(FIRE / current assets) / ln(1 + real return). It needs a positive real return and some money already invested.

Every number below was computed in code from the formulas above and matches the on-page result for the same inputs.

Meaning: this saver needs $1,000,000 to retire on $40,000 a year. Because $250,000 already tops the $231,377 coast number, they could stop adding new money today and still reach the full amount by age 60, or keep contributing and reach it by about age 58.

Four inputs move the result the most. Small changes compound over decades.

Your Safe Withdrawal Rate

This is the biggest lever. A 4 percent rate is the 25x rule; a cautious 3 percent rate is 33 times spending, and a 5 percent rate is 20 times. Lower rates mean a larger, safer FIRE number. The rate is your assumption, not a promise, and sequence-of-returns risk means early bad years hurt most.

Your Annual Spending

The FIRE number scales straight with spending. Cutting yearly costs by $5,000 at a 4 percent rate lowers the target by $125,000. This is why frugality speeds up FIRE more than chasing returns.

Your Expected Real Return

A higher real return shrinks the coast number, because money has more room to grow. It does not change the FIRE number itself. Keep it realistic and after inflation; returns are never guaranteed.

Years Until Retirement

More years between now and retirement push the coast number lower, since compounding has longer to work. Retiring earlier raises the coast number toward the full FIRE number.

Social Security and Pensions

Guaranteed income reduces the spending your portfolio must fund, so it lowers both numbers. Track your overall progress with the net worth calculator.

FIRE is not one finish line. These variations change the spending target or the role of work, and this calculator handles each by adjusting your inputs.

The right target is personal. Many people aim for Coast FIRE first because it frees up cash flow long before full independence, then decide whether to keep pushing to Fat FIRE.

Early in Your Career

Use it to set a Coast FIRE target. Hitting coast early, while compounding has decades to work, is far easier than reaching the full number later.

When Your Income Jumps

Test how a raise or a windfall moves your coast age. A single large investment today can pull your freedom date forward by years.

Before a Big Life Change

Switching to a lower-paying job you love, going part time, or taking a career break are easier to weigh once you know whether you are already Coast FIRE.

At Your Annual Review

Re-run it each year with updated assets and spending. Compare the result with a full drawdown plan from a retirement calculator.

1. Assuming the 4 Percent Rule Is Guaranteed

It is a historical planning guide, not a law. Long retirements, high fees and poor early returns can all require a lower rate. Treat it as an input to test, not a promise.

2. Mixing Nominal and Real Returns

This tool uses a real, after-inflation return so results stay in today's dollars. Do not enter a 10 percent nominal return here, or you will understate your target badly.

3. Forgetting Health Care and Taxes

Early retirees pay for health coverage and still owe taxes on withdrawals. Build those into your spending figure.

4. Ignoring Sequence-of-Returns Risk

A market drop in your first retirement years is more dangerous than the same drop later. A cash buffer and a flexible withdrawal rate help.

5. Treating Coast FIRE as Fully Retired

Coast FIRE means you can stop saving, not stop working. You still need income for today's bills until your portfolio is drawn down.

The calculator reproduces the standard FIRE and Coast FIRE arithmetic exactly for the inputs you give. It is a planning model, not a market forecast.

It is the amount you need invested to retire on your chosen spending. The common rule is annual spending divided by a safe withdrawal rate, so at 4 percent it is 25 times your yearly spending.

Coast FIRE is the smaller amount that grows into your full FIRE number by your target retirement age with no new contributions. Once you reach it you can stop saving for retirement and just cover today's costs.

It is a historical planning guide from the Trinity study and Bengen's 1994 research, not a guarantee. Longer retirements, high fees or poor early returns can call for a lower rate, such as 3 or 3.5 percent.

Enter a real, after-inflation return, for example 5 percent. That keeps your FIRE number and coast number in today's dollars. Using a nominal return here would understate how much you need.

It solves for when your current assets, growing at your real return with no new money, equal your FIRE number: current age plus ln(FIRE divided by current assets) divided by ln(1 plus the real return).

Guaranteed income reduces the spending your portfolio must fund. The tool subtracts it from your spending before dividing by the withdrawal rate, which lowers both your FIRE number and your coast number.

Lean FIRE uses a low spending target, Fat FIRE a high one, and Barista FIRE assumes part-time work covers some costs. Model them by changing your spending figure, or by entering part-time pay as other income.

Yes, and it is common. You can have enough invested to coast to your number by retirement while still needing a paycheck for current bills. The tool shows both the coast status and the full FIRE number.

That happens when your Social Security or pension income is equal to or greater than your spending, so your portfolio does not need to fund anything. Lower the other income to see a portfolio target.

No. It uses the withdrawal rate and real return you enter and applies steady compounding. Real returns vary year to year, so treat the result as a planning estimate, not a forecast.

No. The calculation runs in your browser and nothing is sent to our servers. Anything you choose to Save stays in this browser only.

• Determining Withdrawal Rates Using Historical Data (the origin of the 4 percent rule) (William P. Bengen, Journal of Financial Planning, 1994; read 2026-10-06).
• Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable (the Trinity study) (Cooley, Hubbard and Walz, 1998; read 2026-10-06).
• Compound interest and the time value of money (U.S. Securities and Exchange Commission, Investor.gov; read 2026-10-06).