Calculate your Coast FIRE number instantly with our free Coast FIRE Target Calculator. Find out exactly how much you need to save today so you can stop investing and let compound interest fund your early retirement. Enter your current age, retirement goals, and expected returns to map out your path to financial independence!
Coast FIRE Calculator
What exactly is a Coast FIRE target?
Coast FIRE (Financial Independence, Retire Early) is a financial milestone where you have saved and invested enough money at an early age that you no longer need to contribute to your retirement accounts. Your existing investments will grow through compound interest to reach your full FIRE number by your traditional retirement age.
While "coasting," you do not touch your investments. You still need to work to cover your current living expenses, but because you are no longer burdened with saving for retirement, you can choose lower-stress, part-time, or more fulfilling jobs. It essentially buys you current lifestyle freedom.
How do you calculate your specific Coast FIRE number?
Calculating your Coast FIRE number involves working backward from your traditional retirement target using the compound interest formula.
Formula: Coast FIRE = Full FIRE Number / (1 + Real Interest Rate) ^ Years to Retirement
- Calculate your Full FIRE Number (Annual Expenses / Safe Withdrawal Rate).
- Determine the Years to Retirement (Retirement Age - Current Age).
- Estimate a conservative Real Interest Rate (Expected Return - Inflation).
For example, if you need $1,000,000 at age 65, are currently 35 (30 years to grow), and expect a 5% real return, your calculation is: $1,000,000 / (1.05)^30 = $231,377. Once you hit $231,377 at age 35, you are Coast FIRE.
What is your estimated annual spending for traditional retirement?
Estimated annual spending varies by individual, but a common baseline is 80% of your pre-retirement income. To estimate yours, categorize your future expenses in today's dollars.
| Expense Category | Estimated Monthly | Estimated Annual |
|---|---|---|
| Essentials (Housing, Healthcare, Food) | $3,500 | $42,000 |
| Discretionary (Travel, Hobbies, Dining) | $1,500 | $18,000 |
| Total Projected Spending | $5,000 | $60,000 |
Your specific number will depend heavily on factors like whether your mortgage will be paid off, projected healthcare premiums, and your desired retirement lifestyle.
At what age do you plan to fully retire and touch the funds?
The age you plan to fully retire dictates how many years your investments have to compound untouched. In the Coast FIRE framework, the target retirement age is typically a traditional age (like 60 or 65) rather than an extreme early age.
Choosing your age depends on practical milestones:
- Account Rules: Tax-advantaged accounts like 401(k)s and IRAs impose penalties for withdrawals before age 59½.
- Social Security: Eligibility begins at 62, with full benefits kicking in around 67.
- Healthcare: Medicare eligibility begins at 65 in the US.
Selecting age 65 maximizes your compound growth time, significantly lowering your current Coast FIRE threshold.
What safe withdrawal rate is being used for the final retirement goal?
The most commonly used Safe Withdrawal Rate (SWR) is 4%, based on the historical "Trinity Study." This rule suggests you can withdraw 4% of your portfolio in your first year of retirement, adjust for inflation annually, and likely not run out of money over a 30-year period.
To find your Full FIRE number, you multiply your annual expenses based on your SWR:
- 3% SWR: Annual Expenses × 33.3 (Highly conservative)
- 4% SWR: Annual Expenses × 25 (Standard)
- 5% SWR: Annual Expenses × 20 (Aggressive)
Many modern FIRE adherents prefer a slightly conservative 3.5% SWR to account for longer life expectancies.
What is a realistic expected annual rate of return for the investments?
A realistic expected annual rate of return for a diversified, stock-heavy portfolio (like S&P 500 index funds) is generally 7% to 10% before inflation. However, for Coast FIRE calculations, conservative estimates are much safer.
| Asset Allocation | Nominal Return | Real Return (Post-Inflation) |
|---|---|---|
| 100% Equities | 9-10% | 6-7% |
| 80% Stocks / 20% Bonds | 7-8% | 4-5% |
| Conservative (Heavy Bonds) | 5-6% | 2-3% |
Most FIRE calculators use a 5% to 7% real return. This keeps projections adequately conservative while relying on historical market averages.
How do you properly account for inflation in the growth calculations?
The easiest and most accurate way to account for inflation is to use a real rate of return rather than a nominal rate for your compounding calculations.
Real Return = Nominal Return - Inflation Rate
If you expect your investments to grow by 9% annually (nominal) and inflation to average 3%, your real rate of return is 6%. By using 6% in your Coast FIRE compound interest formula, you calculate everything in today's dollars.
This completely eliminates the need to guess what your expenses will be in 30 years. Your final FIRE number and your Coast FIRE threshold both remain anchored to your current purchasing power.
How much current income is needed to cover living expenses while coasting?
While "coasting," your current income only needs to be exactly equal to your current living expenses. Because your retirement is already fully funded by your past savings, your ongoing savings rate can drop to 0%.
To determine your required income limit:
- Track your monthly baseline expenses (housing, food, transport, insurance).
- Add discretionary spending for your desired lifestyle.
- Account for current income taxes.
If your monthly expenses are $4,000, you only need to earn $48,000 net annually. This drastically lowered income requirement allows "coasters" to switch to part-time work, freelance, or take lower-paying passion jobs.
Does reaching the target mean you should stop investing completely?
Mathematically, yes—reaching your Coast FIRE target means you don't have to invest another cent for retirement. However, in practice, many people do not stop completely.
Strong reasons to continue investing include:
- Employer Matches: Free money from a 401(k) match is highly lucrative and rarely worth skipping.
- Margin of Safety: Future markets could underperform historical averages.
- Lifestyle Inflation: Your future retirement expenses might grow higher than initially estimated.
- Retiring Earlier: Any extra investments will pull your final retirement age closer.
Maintaining small contributions provides a crucial financial safety net.
How often should the Coast FIRE target be reviewed and adjusted over time?
Your Coast FIRE target is a dynamic number and should ideally be reviewed annually.
You should adjust your calculations based on the following triggers:
- Major Life Events: Marriage, having children, or buying a home will drastically change your projected retirement expenses.
- Market Corrections: If a major recession heavily depletes your portfolio, you may briefly fall out of Coast FIRE status and need to resume contributions.
- Prolonged High Inflation: This permanently reduces your real rate of return and purchasing power.
An annual check-up ensures your investments remain on track and allows you to pivot smoothly if your goals change.
Sources:
Barista FIRE Income Gap Calculator