Coast FIRE Calculator

Q: What is a good safe withdrawal rate to use?

The best-known starting point is the 4% rule. 3 In the Trinity Study, a 4% first-year withdrawal adjusted for inflation lasted 30 years in 95% to 98% of past periods for portfolios holding 50% to 100% stocks. 2 For a retirement lasting longer than 30 years, such as early retirement, a lower rate is safer: in Bengen's study, for a portfolio rebalanced to half stocks and half intermediate-term Treasuries, about 3.5% or less never left it lasting under 50 years. 1 A higher rate is riskier but means you need less money saved. In the Trinity Study, 5% lasted 30 years in only 76% to 85% of past periods for the same portfolios. 2 Choose a rate based on how long your retirement might last and how flexible your spending can be.

Introduction

Coast FIRE is a milestone on the path to financial independence where you've saved enough that your investments will grow to your full retirement number on their own, even if you never invest another dollar. Once you hit your Coast FIRE number, compound growth does the heavy lifting, and you only need to earn enough to cover your current living expenses. This frees you to take a lower-paying job, work part-time, or simply remove the pressure of aggressive saving from your life.

Our Coast FIRE Calculator helps you find three key things: your FIRE target number (the total portfolio you need to retire), your Coast FIRE number (how much you need saved right now so growth alone finishes the job), and your Coast FIRE age (when your portfolio crosses that threshold based on your monthly contributions). Just enter your age, savings, contributions, expected returns, and spending goals. The calculator adjusts every result for inflation so you see numbers in today's dollars, giving you an honest picture of your future purchasing power. A year-by-year table and interactive chart show exactly how your portfolio stacks up against the Coast FIRE curve over time.

How to Use Our Coast FIRE Calculator

Enter your age, savings, and retirement goals below, and this calculator will tell you your Coast FIRE number: the amount you need saved so your money can grow to your full retirement target on its own, with no more contributions needed.

Current Age: Enter how old you are right now. This is the starting point for all projections.

Target Retirement Age: Enter the age when you want to stop working and begin living off your investments.

Current Invested Assets: Enter the total value of your invested accounts, such as a 401(k), Roth IRA, or brokerage account. Do not include your emergency fund, checking account, or money that is not invested.

Monthly Contribution: Enter how much money you add to your investments each month. This is the amount you save and invest on a regular basis.

Annual Spending in Retirement: Enter how much money you expect to spend each year once you retire. Think about your living costs, healthcare, travel, and hobbies.

Pre-Retirement Annual Return: Enter the yearly return you expect your investments to earn before you retire. A common estimate for a stock-heavy portfolio is 7%.

Expected Inflation Rate: Enter the rate at which you expect prices to rise each year. U.S. inflation averaged 3% a year over the long history Bengen studied.¹ The calculator uses this to show all results in today's dollars so you can see the real purchasing power of your money.

Safe Withdrawal Rate (SWR): Enter the share of your savings you plan to withdraw in your first year of retirement. The 4% rule is a widely used starting point.³ Under it, you take out 4% of your savings in the first year, then raise that dollar amount with inflation each year.¹

What Is Coast FIRE?

Coast FIRE is a milestone on the path to financial independence where you have saved enough money that, even if you never invest another dollar, your portfolio will grow on its own to support your retirement by your target age. Once you hit your Coast FIRE number, compound interest does all the heavy lifting. You still need to cover your living expenses, but you no longer need to save for retirement.

How Coast FIRE Works

The idea behind Coast FIRE is simple. Money that is invested grows over time thanks to compound returns. If you save aggressively early in life, there comes a point where your investments will compound to a large enough amount by retirement age, without any extra contributions. At that point, you are "coasting." You could switch to a lower-paying job you enjoy more, work part-time, or simply stop stressing about your savings rate.

Key Numbers You Need to Know

FIRE Target Number: This is the total amount you need in your portfolio to retire and live off your investments. It is calculated by dividing your expected annual spending in retirement by your safe withdrawal rate (SWR). For example, if you plan to spend $40,000 per year and use a 4% withdrawal rate, your FIRE target is $1,000,000.

Coast FIRE Number: This is how much you need to have saved right now so that it grows to your FIRE target by retirement, with zero additional contributions. It depends on your FIRE target, your age, your target retirement age, and your expected real rate of return (your investment return with inflation taken out).

Coast FIRE Age: If you haven't yet reached your Coast FIRE number, this tells you the age at which your growing portfolio (with continued contributions) will cross the Coast FIRE threshold.

Why Inflation Matters

A dollar today will not buy the same amount of goods 30 years from now. That is why this calculator adjusts all values for inflation. It uses the "real" rate of return, which is your investment return with the effect of inflation taken out. This way, every number you see reflects actual purchasing power in today's dollars, giving you an honest and useful picture of your future finances.

The Safe Withdrawal Rate

The safe withdrawal rate is the share of your portfolio you take out in the first year of retirement. After that, the dollar amount is adjusted for inflation each year.¹ The best-known starting point is the 4% rule, which grew out of William Bengen's 1994 study.³ A later study often called the Trinity Study found that withdrawing 4% of your portfolio in the first year, then adjusting for inflation, lasted 30 years in 95% to 98% of past periods for portfolios holding 50% to 100% stocks.² If you want to be more conservative or plan for a longer retirement, you might choose a lower rate. In Bengen's study, for a portfolio rebalanced to half stocks and half intermediate-term Treasuries, a starting rate of about 3.5% or less never left it lasting under 50 years.¹

How to Use Your Results

If the calculator shows you have already reached Coast FIRE, that means your current savings will grow to your FIRE target on their own. Any extra money you invest from this point forward is a bonus that could let you retire earlier or with more spending flexibility.

If you haven't reached Coast FIRE yet, the calculator shows the age when you will reach it if you keep saving the monthly amount you entered, or tells you if that amount will not get you there before retirement. The year-by-year table and chart let you track your progress at every age along the way.

Tips to Reach Coast FIRE Faster

Start early. The younger you are, the more time compound growth has to work. Even small amounts invested in your 20s can make a huge difference.
Increase your savings rate. Bumping your monthly contribution by even $100 can shave years off your Coast FIRE age.
Keep expenses in check. A lower annual spending target means a smaller FIRE number, which means a smaller Coast FIRE number.
Stay invested. Pulling money out or sitting in cash slows compound growth. Keep your invested assets working for you through market ups and downs.
Maximize tax-advantaged accounts. Contributions to your 401(k), Roth IRA, or HSA grow tax-free or tax-deferred, letting more of your returns compound without being reduced by taxes.

Formulas used

FIRE Target Number

\text{FIRE Target} = \frac{\text{Annual Spending}}{\text{SWR}}

Real Rate of Return (Inflation-Adjusted)

r_{\text{real}} = \frac{1 + r_{\text{nominal}}}{1 + r_{\text{inflation}}} - 1

Coast FIRE Number at Current Age

\text{Coast FIRE} = \frac{\text{FIRE Target}}{(1 + r_{\text{real}})^{n}}

Coast FIRE Number at Any Age

\text{Coast}_{\text{age}} = \frac{\text{FIRE Target}}{(1 + r_{\text{real}})^{\,\text{Retirement Age} - \text{Age}}}

Annual Portfolio Growth

B_{t} = B_{t-1} + C_{\text{annual}} + B_{t-1} \times r_{\text{real}}

Retirement Income (Annual)

\text{Retirement Income} = \text{Projected Portfolio} \times \text{SWR}

Surplus / Shortfall

\text{Surplus} = \text{Projected Portfolio at Retirement} - \text{FIRE Target}

Frequently asked questions

What is the difference between Coast FIRE and regular FIRE?

Regular FIRE means you have saved enough to retire right now and live off your investments. Coast FIRE means you have saved enough that your money will grow to your full retirement number on its own by your target age, but you still need to work to cover your current living expenses. Coast FIRE is a halfway point. You stop saving for retirement but keep earning enough to pay your bills today.

How is the Coast FIRE number calculated?

The calculator first finds your FIRE target by dividing your annual retirement spending by your safe withdrawal rate. Then it figures out how much money you would need today so that it grows to that FIRE target by your retirement age using compound growth. The formula is: Coast FIRE Number = FIRE Target ÷ (1 + real rate of return) ^ years until retirement. The real rate of return is (1 + your return) ÷ (1 + inflation) − 1, which takes inflation out of your return.

What should I do after I reach Coast FIRE?

Once you reach Coast FIRE, you no longer need to save for retirement. If they earn the return you entered, your investments will grow to your target on their own. You can keep working but switch to a job you enjoy more, work fewer hours, or take a pay cut without hurting your retirement plan. You just need to earn enough to cover your current bills. Any extra money you invest after Coast FIRE lets you retire even earlier or with more spending room.

What is a good safe withdrawal rate to use?

The best-known starting point is the 4% rule.³ In the Trinity Study, a 4% first-year withdrawal adjusted for inflation lasted 30 years in 95% to 98% of past periods for portfolios holding 50% to 100% stocks.² For a retirement lasting longer than 30 years, such as early retirement, a lower rate is safer: in Bengen's study, for a portfolio rebalanced to half stocks and half intermediate-term Treasuries, about 3.5% or less never left it lasting under 50 years.¹ A higher rate is riskier but means you need less money saved. In the Trinity Study, 5% lasted 30 years in only 76% to 85% of past periods for the same portfolios.² Choose a rate based on how long your retirement might last and how flexible your spending can be.

What rate of return should I use for pre-retirement?

A 7% nominal return is a common, cautious estimate for a portfolio heavily invested in stocks. Over the long history Bengen studied, U.S. common stocks returned 10.3% a year and intermediate-term Treasuries 5.1%, before inflation.¹ If your portfolio includes a lot of bonds or other conservative investments, you might use a lower number like 5% or 6%. The calculator takes inflation out of this number to get your real rate of return.

Should my investment mix change after I retire?

It depends on the mix you hold. In Bengen's study, the best mix to start retirement with was 50% to 75% in stocks, and for most retirees that mix could be kept throughout retirement or until their goals changed.¹ Less than 50% in stocks made the portfolio run out sooner in its worst periods, and more than 75% did the same in a Depression-like period, so he advised against either at the start of retirement.¹ The calculator uses only your pre-retirement return, because the Coast FIRE number comes from how your savings grow before you retire.

Can I reach Coast FIRE if I start late?

Yes, but it is harder. When you start later, your money has fewer years to compound, so your Coast FIRE number is higher and closer to the full FIRE target. You may need to save more each month or plan for a later retirement age. The calculator lets you adjust all of these inputs so you can find a plan that works for your situation.

Should I include my home value in current invested assets?

No. Only include assets that are actually invested and growing, like money in a 401(k), IRA, Roth IRA, or brokerage account. Your home, car, emergency fund, and checking account should not be counted. The calculator grows everything you enter here at your expected return, so count only money that is invested.

How does changing inflation affect my Coast FIRE number?

Higher inflation reduces your real rate of return, which means your money grows slower in terms of purchasing power. This makes your Coast FIRE number higher because you need more money today to reach the same goal. Lower inflation has the opposite effect: your real returns are stronger and your Coast FIRE number drops. Even a small change in inflation can make a big difference over 20 or 30 years.

Is Coast FIRE the same as Barista FIRE?

They are very similar. Coast FIRE means your investments will grow to your retirement goal without more contributions, and you just need to cover current expenses. Barista FIRE usually refers to working a part-time or low-stress job (sometimes one that provides health insurance) to cover those expenses. A part-time job like this is one way to cover your bills after reaching Coast FIRE.

Sources

Bengen WP. Determining Withdrawal Rates Using Historical Data. Journal of Financial Planning. 1994;October 1994, reprinted March 2004. Accessed September 27, 2026.

Cooley PL, Hubbard CM, Walz DT. Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable. AAII Journal. 1998;February 1998, Table 3. Accessed September 27, 2026.

Pfau WD. An International Perspective on Safe Withdrawal Rates: The Demise of the 4 Percent Rule? Journal of Financial Planning. 2010;December 2010, 23(12):52-61, introduction (pages 52 and 53). Accessed November 12, 2026.

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