Coast FIRE (Coast Financial Independence, Retire Early) is the point where your existing investments are projected to grow to your full retirement target by your chosen retirement age—without requiring additional retirement contributions. You still need income for today’s expenses, but compound growth may be able to do the rest of the work for your future retirement.
Want to see where you stand? Use our free Coast FIRE Calculator to estimate your number in seconds.
How Does Coast FIRE Work?
Coast FIRE works backward from your retirement goal.
Instead of asking, “How much do I need to keep saving every month?”, it asks:
How much would I need invested today for compound growth to potentially take my portfolio to my retirement target?
That amount is your Coast FIRE number.
The concept depends heavily on time. The more years your investments have to compound, the less you generally need invested today to reach the same future target.
Once you reach Coast FIRE, you don’t necessarily retire or stop working. You still need income to cover your current living expenses.
What changes is that you may have more flexibility over how much of today’s income needs to be directed toward retirement.
The Coast FIRE Formula
Calculating your Coast FIRE number takes two steps.
Step 1: Calculate Your Full FIRE Number
First estimate the portfolio you would need at retirement:
FIRE Number = Annual Retirement Spending ÷ Safe Withdrawal Rate
For example, if you expect to spend $60,000 per year and use a 4% withdrawal rate:
$60,000 ÷ 0.04 = $1,500,000
Your Full FIRE Number would be $1.5 million.
Want to calculate your full FIRE target? Try our FIRE Calculator.
The 4% withdrawal rate is a commonly used retirement-planning benchmark, not a guarantee. Historical research shows that sustainable withdrawal rates depend on factors such as portfolio allocation, retirement horizon, and inflation.
Step 2: Calculate Your Coast FIRE Number
Now discount that future target back to today:
Coast FIRE Number = FIRE Number ÷ (1 + Real Annual Return)^Years Until Retirement
The key word here is real.
A real return accounts for inflation, allowing us to express today’s savings and future retirement spending in today’s purchasing power.
Coast FIRE Example: Age 35
Let’s use the same assumptions as the Independence Compass Coast FIRE Calculator:
- Current age: 35
- Retirement age: 60
- Annual retirement spending: $60,000
- Current invested savings: $150,000
- Safe withdrawal rate: 4%
- Expected real annual return: 7%
First:
Full FIRE Number = $60,000 ÷ 4% = $1,500,000
There are 25 years until retirement, so:
Coast FIRE Number = $1,500,000 ÷ (1.07)^25
Coast FIRE Number ≈ $276,000
With $150,000 currently invested, the remaining gap would be approximately:
$276,000 − $150,000 = $126,000
If the existing $150,000 earned an average 7% real return for 25 years without additional contributions, it would grow to approximately $814,000 in today’s dollars.
That doesn’t mean the portfolio will produce those results. It shows what happens under the assumptions entered.
Try your own age, spending, and return assumptions in our Coast FIRE Calculator.
Coast FIRE by Age: How Much Would You Need?
Here’s where compound growth becomes easier to see.
The table below assumes:
- Retirement at age 60
- Annual retirement spending of $60,000
- 4% withdrawal rate
- Full FIRE target of $1.5 million
- No additional contributions
| Current Age | Years to 60 | 5% Real Return | 6% Real Return | 7% Real Return |
|---|---|---|---|---|
| 25 | 35 | $272K | $195K | $140K |
| 30 | 30 | $347K | $261K | $197K |
| 35 | 25 | $443K | $350K | $276K |
| 40 | 20 | $565K | $468K | $388K |
| 45 | 15 | $722K | $626K | $544K |
| 50 | 10 | $921K | $838K | $763K |
These aren’t recommended targets or forecasts. They’re examples showing how dramatically age and return assumptions change your Coast FIRE number.
At age 30, for example, the same $1.5 million retirement target requires approximately $197K today at a 7% real return—but approximately $347K using 5%.
That’s a difference of roughly $150,000 created entirely by changing one assumption.
This is why stress-testing matters.
What Return Should You Use for Coast FIRE?
There is no single correct return assumption.
Historically, U.S. equities have generated strong long-term returns, but actual results vary considerably depending on the period measured.
Our calculator defaults to 7% real annual return as a historical long-term equity assumption.
But 7% is not a forecast.
A useful approach is to run multiple scenarios:
- 5% real return: More conservative stress test
- 6% real return: Moderate scenario
- 7% real return: Historical long-term equity scenario
If your Coast FIRE plan only works at 7%, that’s useful information.
Try 5% and 6% too. A plan that still works under less favorable assumptions gives you a larger margin for uncertainty.
Coast FIRE vs. Full FIRE vs. Barista FIRE
These terms are related but describe different situations.
Full FIRE means your portfolio has reached the amount you estimate is necessary to support your lifestyle without relying on employment income.
Coast FIRE means your portfolio hasn’t reached Full FIRE yet, but your existing investments are projected to grow to your future retirement target without additional contributions.
Barista FIRE generally describes a form of partial financial independence where you continue earning some income—often through part-time or lower-stress work—while investments cover or eventually grow toward the rest of your financial needs.
The simplest distinction is:
Full FIRE = enough invested for today.
Coast FIRE = potentially enough invested for the future.
Barista FIRE = investments + some continued earned income.
What Changes When You Reach Coast FIRE?
The biggest benefit isn’t necessarily that you can stop saving.
It’s optionality.
Someone who reaches Coast FIRE could continue investing aggressively and potentially reach Full FIRE earlier.
Another person might reduce retirement contributions and work fewer hours.
Someone else might change careers, start a business, take a sabbatical, or simply use more of today’s income for current priorities.
You don’t have to change anything.
Coast FIRE simply gives you another way to evaluate how much financial flexibility you’ve already built.
What Could Make Your Coast FIRE Number Wrong?
Coast FIRE is a planning model, not a prediction.
Your result depends on assumptions about:
- future investment returns;
- retirement spending;
- inflation;
- withdrawal rates;
- retirement age;
- investment fees and taxes; and
- how your portfolio changes over time.
Market returns also don’t arrive as a smooth 5%, 6%, or 7% every year.
A long investment horizon can include crashes, recoveries, and extended periods of weaker or stronger returns.
That’s why the most useful Coast FIRE number isn’t necessarily the one produced by your favorite assumptions.
It’s the range you see after testing several reasonable scenarios.
How Do You Know If You’ve Reached Coast FIRE?
The basic comparison is simple:
Current Invested Savings ≥ Coast FIRE Number
Using our age-35 example:
Coast FIRE Number: $276,000
Current Investments: $150,000
Remaining Gap: $126,000
Under those assumptions, Coast FIRE hasn’t been reached yet.
But instead of vaguely wondering whether you’re “on track,” you now have a measurable milestone.
Calculate Your Coast FIRE Number
Coast FIRE isn’t about finding one perfect number.
It’s about understanding how time, spending, and investment assumptions interact.
Use the Independence Compass Coast FIRE Calculator to test your own numbers.
Try your expected scenario first.
Then change the real return from 7% to 6% and 5%.
Change your retirement age.
Change your expected spending.
The goal isn’t to find the scenario that gives you the smallest Coast FIRE number.
It’s to understand how resilient your plan is when the assumptions change.
Calculate Your Coast FIRE Number →
Frequently Asked Questions
What is Coast FIRE?
Coast FIRE is the point where your existing investments are projected to grow to your full retirement target by your chosen retirement age without additional retirement contributions.
How do I calculate my Coast FIRE number?
First calculate your Full FIRE Number using expected annual retirement spending divided by your withdrawal rate. Then discount that future target back to today using your expected real investment return and the number of years until retirement.
What is the Coast FIRE formula?
Coast FIRE Number = FIRE Number ÷ (1 + Real Annual Return)^Years Until Retirement
How much do I need for Coast FIRE at 30?
Using a $1.5 million Full FIRE target and retirement age of 60, the illustrative Coast FIRE number is approximately $347K at 5% real return, $261K at 6%, or $197K at 7%.
Your actual number depends on your own spending, retirement age, withdrawal rate, and return assumptions.
How much do I need for Coast FIRE at 40?
Using the same $1.5 million target and retirement at 60, the illustrative Coast FIRE number is approximately $565K at 5%, $468K at 6%, or $388K at 7% real return.
Can I stop saving after reaching Coast FIRE?
That’s what the mathematical model assumes, but you don’t have to. Continuing to invest can create additional margin for lower-than-expected returns, changing expenses, or an earlier retirement.
Is 7% a reasonable return for Coast FIRE?
A 7% real return can be used as a historical long-term U.S. equity scenario, but it shouldn’t be treated as a guaranteed future return. Testing 5%, 6%, and 7% scenarios provides a better view of how sensitive your Coast FIRE number is to investment performance.
Is Coast FIRE the same as Barista FIRE?
No. Coast FIRE focuses on having enough invested today for compound growth to potentially fund your future retirement target. Barista FIRE generally combines an existing investment portfolio with continued earned income, often from part-time or lower-stress work.