Coast FIRE Calculator
How much do you need invested today so that – without saving another dollar – your portfolio grows to your full FIRE number by retirement? Enter your age, portfolio and spending: the calculator shows your Coast FIRE number, whether you have reached it, and at what age you will.
- Coast FIRE number, gap and the age you reach it
- Cautious, base and optimistic scenarios plus a year-by-year projection
- Barista FIRE: see what part-time income changes
- Your numbers stay in your browser – nothing is sent to us
Your numbers (today's dollars)
Your Coast FIRE number today
–
invested today grows to your FIRE number in – without new contributions.
- FIRE number
- –
- Gap to Coast FIRE today
- –
- Coast FIRE reached at age
- –
- Today's portfolio at retirement, no new contributions
- –
Barista FIRE number
–
Barista Coast FIRE number today
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- With your monthly contributions
- Without new contributions
- Coast FIRE number at that age
Show the year-by-year table
| Age | With contributions | Without contributions | Coast FIRE number | Reached? |
|---|
Scenarios
| Scenario | Real return | Coast FIRE number | Reached? |
|---|
Cautious = your return minus 2 percentage points, optimistic = plus 1 percentage point. Returns vary from year to year; this projection uses a constant average.
Coast FIRE Spreadsheet for Excel and Google Sheets
- The same formulas as this calculator, pre-filled with your numbers – change any input and everything updates
- Your own cautious, base and optimistic returns side by side
- Year-by-year projection up to retirement, with the age you reach Coast FIRE
- Barista FIRE variant and a notes sheet with every formula and source
.xlsx file, created in your browser right after purchase; opens in Excel and can be imported into Google Sheets. Educational tool – not investment, tax or financial advice.
€9.00
charged in euros · incl. VAT where applicable
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Download your spreadsheet here – now or later, without paying again. It is created from the numbers in the calculator above. For Google Sheets: File → Import → Upload the .xlsx file.
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Open formulas and sources
Every default value is shown with its source and date below.
Your data stays with you
Runs in your browser. No cookies, no tracking, no account.
No promises
A planning tool with stated assumptions – not investment advice.
How the Coast FIRE calculator works
Coast FIRE means you have invested enough that compound growth alone carries your portfolio to your full FIRE number by your target retirement age. From then on you only need to earn enough to cover your current spending – you can “coast” instead of saving aggressively.
- FIRE number = annual spending in retirement ÷ safe withdrawal rate. At 4% that is 25 × your spending: $40,000 a year needs $1,000,000.
- Coast FIRE number = FIRE number ÷ (1 + real return)years until retirement. With 6% real return and 35 years to go, $1,000,000 ÷ 1.0635 ≈ $130,105.
- Reached? If your portfolio today is at least the Coast FIRE number, yes. In the example, $100,000 is not yet enough – but with $1,000 a month, the portfolio passes the (rising) Coast FIRE number at age 33.
- Barista FIRE = (spending − part-time income) ÷ withdrawal rate. Part-time income of $20,000 halves the $1,000,000 in the example to $500,000.
Simplifications: constant average real return; monthly contributions are added once a year (at year end); no taxes, fees or Social Security. All amounts are in today's dollars because the return is after inflation.
Coast FIRE number as a share of your FIRE number
How much of your final FIRE number you need invested today, depending on years until retirement and real return (calculated as 1 ÷ (1 + return)years, rounded):
| Years to retirement | 4% real | 5% real | 6% real | 7% real |
|---|---|---|---|---|
| 10 | 68% | 61% | 56% | 51% |
| 15 | 56% | 48% | 42% | 36% |
| 20 | 46% | 38% | 31% | 26% |
| 25 | 38% | 30% | 23% | 18% |
| 30 | 31% | 23% | 17% | 13% |
| 35 | 25% | 18% | 13% | 9% |
| 40 | 21% | 14% | 10% | 7% |
Example: 30 years before retirement at 6% real return, 17% of a $1,000,000 FIRE number – $174,110 – is enough to coast.
Where the default values come from
| Value | Source | As of |
|---|---|---|
| 4% safe withdrawal rate | Trinity study: Cooley, Hubbard, Walz, “Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable”, AAII Journal, 1998 (US data 1925–1995; for inflation-adjusted withdrawals: “withdrawal rates of 3% to 4% continue to produce high portfolio success rates for stock-dominated portfolios”), summarized on Wikipedia | retrieved Oct 3, 2026 |
| 6% real return (default) | Our assumption, set below the historical average of about 6.8% a year (calculated below) | Oct 2026 |
| S&P 500 incl. dividends, 1928–2025: $100 → $1,157,598.95 (≈ 10.0% a year before inflation) | A. Damodaran, NYU Stern, Historical Returns on Stocks, Bonds and Bills | updated Jan 5, 2026 |
| US consumer prices (CPI-U): 17.3 (Dec 1927) → 324.054 (Dec 2025); real ≈ 6.8% a year | U.S. Bureau of Labor Statistics via FRED, series CPIAUCNS; real return our calculation | retrieved Oct 3, 2026 |
| Scenarios: −2 / +1 percentage points | Our assumption | Oct 2026 |
Past returns do not guarantee future results. Next review of these values: before January 1, 2027.
Frequently asked questions
The amount you need invested today so that, with no further contributions, it grows to your FIRE number by your target retirement age. It depends on your spending, your withdrawal rate, the real return you expect and the years you have left.
A real return is the return after inflation. Using it keeps every amount in today's dollars, so your spending and FIRE number stay comparable to what things cost now. If you expect, say, 9% nominal and 3% inflation, enter about 6%.
It comes from historical US data (1925–1995) for payout periods of 15 to 30 years. Early retirements often last longer than that, and history is no guarantee, so it is worth testing a lower rate such as 3% or 3.5% – a lower rate means a higher FIRE and Coast FIRE number.
With Coast FIRE you keep working to pay your current bills but stop saving for retirement. With Barista FIRE you already retire from full-time work and a part-time job covers part of your spending, so you need a smaller portfolio. Enter part-time income to see both.
An Excel file (.xlsx) with the calculator's formulas, your numbers pre-filled, editable scenarios, a year-by-year projection and a Barista FIRE section. It also imports into Google Sheets. It is created in your browser after you pay, so your numbers never reach us.
Not by us. The calculator runs in your browser. Only if you click “Buy the spreadsheet” does your browser keep your numbers locally on your device so the spreadsheet can be filled with them; you can delete them with one click.
Educational tool, not investment, tax or financial advice. Results are estimates based on your inputs and the stated assumptions. For decisions about your own situation, talk to a licensed financial professional.