Coast FIRE Number Calculator
Example: Retirement target (FIRE number): 1500000 $ · Amount already saved: 150000 $ · Monthly savings toward investment: 1500 $ · Expected annual return: 7 % · Years until you want to retire: 30 years
| Your Coast FIRE number | $197,051 |
| Surplus (+) or shortfall (−) vs. saved | $-47,051 |
| Months of saving to reach Coast FIRE | 31.37 |
| Amount currently saved | $150,000 |
Worked example
If you want $1.5 million in 30 years at a 7% return, your Coast FIRE number is $196,767. You have $150,000 saved — so you are $46,767 short. At $1,500 per month in savings, you reach your Coast FIRE number in about 31 months, after which you can stop contributing entirely and let compounding finish the job.
Frequently asked questions
What happens if I keep contributing after hitting Coast FIRE?
You accelerate your retirement date or end up with a larger portfolio than your target — both fine outcomes. Coast FIRE is a minimum checkpoint, not a ceiling. Many people find it motivating to know they have won the core battle and can ease off, while continuing to contribute if their income allows.
What is a good FIRE number to use as my target?
A common rule of thumb is 25 times your expected annual retirement spending, based on the 4% safe withdrawal rate from the Trinity Study (1998). For example, if you plan to spend $60,000 per year, your FIRE number would be $1.5 million. The actual safe withdrawal rate varies by retirement length, asset allocation, and market conditions.
Does the Coast FIRE calculation account for inflation?
No — this tool uses nominal returns and nominal targets. If your retirement target is in today's dollars, use an inflation-adjusted real return (nominal return minus expected inflation) to get a comparable real Coast FIRE number. Using 4–5% real return instead of 7% nominal is a common conservative adjustment.