Coast FIRE Calculator
Calculate when you can stop saving for retirement and let compound growth do the rest.
=retirement_target / (1 + return_rate)^years_until_retirement How It Works
Coast FIRE (or Coast FI) is the point where you’ve saved enough that compound growth alone will get you to your retirement goal - even if you never save another dollar. Once you hit Coast FIRE, you only need to earn enough to cover current expenses.
The Formula
Coast FIRE Number:
=retirement_target / (1 + annual_return)^years_until_retirementThis calculates how much you need TODAY for it to grow to your target by retirement.
Example
Your Situation:
- Target Retirement Age: 65
- Current Age: 35
- Years Until Retirement: 30
- Retirement Target: $1,500,000
- Expected Return: 7%
Coast FIRE Number:
=$1,500,000 / (1.07)^30 = $197,105If you have $197,105 at age 35, you can stop saving and it will grow to $1.5M by 65 at 7% returns.
Coast FIRE by Age
How much you need at each age to coast to $1,500,000 at 65 (7% return):
| Current Age | Years to 65 | Coast Number |
|---|---|---|
| 25 | 40 | $100,186 |
| 30 | 35 | $140,495 |
| 35 | 30 | $197,105 |
| 40 | 25 | $276,416 |
| 45 | 20 | $387,693 |
| 50 | 15 | $543,791 |
| 55 | 10 | $762,617 |
| 60 | 5 | $1,069,480 |
The earlier you start, the smaller your Coast number.
Building a Coast FIRE Calculator
| Input | Value |
|---|---|
| Current Age | 35 |
| Target Retirement Age | 65 |
| Annual Expenses in Retirement | $50,000 |
| Withdrawal Rate | 4% |
| Expected Investment Return | 7% |
| Current Retirement Savings | $150,000 |
| Output | Formula |
|---|---|
| Years Until Retirement | =B2-B1 |
| Retirement Target (25x) | =B3/B4 |
| Coast FIRE Number | =B8/(1+B5)^B7 |
| Progress to Coast | =B6/B9 |
| Years Until Coast | =NPER(B5,0,-B6,B9) |
Results:
- Retirement target: $1,250,000
- Coast number at 35: $164,254
- Current progress: 91%
- Years until Coast: ~1.3 years
When Will You Hit Coast FIRE?
If you’re not there yet, calculate when you will be:
=NPER(return_rate, -annual_savings, -current_savings, coast_number)Example:
- Current savings: $100,000
- Annual savings: $20,000
- Coast target: $197,105
- Return: 7%
=NPER(7%, -20000, -100000, 197105) = 3.8 yearsCoast FIRE vs. Full FIRE
| Type | Definition | Required Savings |
|---|---|---|
| Coast FIRE | Enough that growth covers retirement | ~$150-300K typically |
| Barista FIRE | Coast + part-time work for expenses | Same as Coast |
| Lean FIRE | Retire on minimal expenses | ~$625K (25x $25K) |
| Regular FIRE | Retire on normal expenses | ~$1-1.5M |
| Fat FIRE | Retire with abundance | $2.5M+ |
The Freedom of Coast FIRE
Once you hit Coast FIRE, you need to earn only your current expenses:
| Annual Expenses | Monthly Needed | Hourly @ Full-Time |
|---|---|---|
| $30,000 | $2,500 | ~$14/hr |
| $40,000 | $3,333 | ~$19/hr |
| $50,000 | $4,167 | ~$24/hr |
| $60,000 | $5,000 | ~$29/hr |
No more saving for retirement. Just cover today’s bills.
Sensitivity Analysis
How different returns affect your Coast number (targeting $1.5M at 65, currently 35):
| Return Rate | Coast Number | Difference |
|---|---|---|
| 5% | $347,032 | Baseline |
| 6% | $261,178 | -$85K |
| 7% | $197,105 | -$150K |
| 8% | $149,029 | -$198K |
| 9% | $112,892 | -$234K |
Conservative assumptions require a higher Coast number.
Multiple Coast FIRE Scenarios
Plan for different retirement ages:
| Retire At | Years | Coast Number | Status |
|---|---|---|---|
| 55 | 20 | $387,693 | Not yet |
| 60 | 25 | $276,416 | Close |
| 65 | 30 | $197,105 | Achieved! |
| 67 | 32 | $171,234 | Achieved! |
You might hit Coast for 65 retirement while still working toward 55 retirement.
Barista FIRE Calculation
Coast FIRE + part-time income for healthcare:
=coast_expenses + healthcare_costExample:
- Living expenses: $35,000
- Healthcare (ACA): $8,000
- Barista FIRE income needed: $43,000
At $20/hr part-time (25 hrs/week): $26,000 Remaining gap to cover: $17,000
Factoring in Social Security
If you’ll receive Social Security, you can adjust:
=((retirement_expenses - social_security) / withdrawal_rate) / (1 + return)^yearsSocial Security reduces your retirement target, which reduces your Coast number.
Example:
- Expenses: $50,000
- Social Security: $20,000
- Gap: $30,000
- Target: $750,000 (instead of $1.25M)
- Coast number: $98,522 (instead of $164,254)
The Psychological Benefits
Coast FIRE provides:
- Reduced career stress - you can take risks, switch jobs, try new things
- Negotiating power - you don’t NEED the job for retirement
- Work-life balance - choose jobs for fulfillment, not salary
- Downshift options - take lower-paying but more enjoyable work
Pro Tips
-
Use conservative returns - 5-6% is safer than assuming 10%
-
Keep some savings momentum - even after Coast, some saving provides buffer
-
Don’t forget healthcare - the biggest Barista FIRE expense before 65
-
Recalculate annually - market changes affect your Coast status
-
Consider inflation - your retirement target should be in future dollars
Common Errors
- Too aggressive returns: 7% is reasonable long-term, but not guaranteed
- Forgetting inflation: $1M in 30 years isn’t $1M today
- Ignoring healthcare: You still need insurance if you stop working
- Touching retirement funds: Coast only works if you let the money grow