Coast FIRE Number
Your Coast FIRE number is the dollar amount you need invested today for compounding alone to grow into a full retirement portfolio. Below: the formula, examples by age, and a free tool to find yours.
The Coast FIRE number formula
FIRE Number = Annual Retirement Spending / Safe Withdrawal Rate Coast FIRE Number = FIRE Number / (1 + Real Return) ^ Years Until Retirement
Real return = return after inflation. A 4–6% real return is a common assumption for a globally diversified stock portfolio. Run your own scenario in the Coast FIRE tracker.
Coast FIRE number by age
Assumes a $1,250,000 FIRE goal ($50k annual spending at 4% SWR), 5% real return, retirement at 65. Your number scales linearly with spending.
| Current Age | Years to Retire | Coast FIRE Number |
|---|---|---|
| 25 | 40 | $177,500 |
| 30 | 35 | $226,500 |
| 35 | 30 | $289,200 |
| 40 | 25 | $369,200 |
| 45 | 20 | $471,100 |
| 50 | 15 | $601,400 |
Calculate your Coast FIRE number
Live calculation — change any field to see your Coast FIRE number update.
Ages 32–65. Real (inflation-adjusted) returns shown — change the inputs above to compare scenarios.
Educational tool only — not financial, tax, or investment advice.
Why your number changes every year
The Coast FIRE number isn't fixed. Each year you don't reach it, the discount window shrinks and the required amount goes up. Markets, inflation, and changes to your retirement spending also move the target. That's why most people benefit more from a recurring Coast FIRE tracker than a one-time calculation.
Frequently asked questions
What is a Coast FIRE number?▾
Your Coast FIRE number is the amount you need invested today so that — with zero additional contributions — compound growth alone reaches your full FIRE number by your target retirement age.
How do I calculate my Coast FIRE number?▾
Take your annual retirement spending and divide by your safe withdrawal rate (typically 4%) to get your FIRE number. Then divide that by (1 + expected real return) raised to the years until retirement.
What is a good Coast FIRE number at age 30?▾
With a $1.25M FIRE goal, a 5% real return, and retirement at 65, the Coast FIRE number at 30 is roughly $226,000. Your number scales linearly with your annual spending — double the spending, double the Coast FIRE number.
Does my Coast FIRE number change over time?▾
Yes. As you age, the number rises because you have fewer years for compounding to do the work. That's why tracking it monthly with a Coast FIRE tracker matters more than calculating once.
Track your number month over month
Calculating once tells you where you stand today. Tracking shows you the trajectory.
Open the Coast FIRE TrackerRelated calculators
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