The free Coast FIRE calculator shows how much you need invested today for growth alone to reach your FIRE number. That number is the portfolio that funds a year of retirement spending at your withdrawal rate. A 30-year-old retiring at 60 on $60,000 a year needs $347,066.17 now, at a 5% real return and a 4% withdrawal rate.
Coast FIRE number (needed today)
$478,293.71
You need $478,293.71 invested at age 30 to reach $1,500,000.00 by age 60 with no further contributions.
Informational only, not financial advice.
31% of your Coast FIRE number is invested
- Coast FIRE number (needed today)
- $478,293.71
- FIRE number at retirement
- $1,500,000.00
- Your investments at retirement, no new contributions
- $470,422.24
- Shortfall today
- $328,293.71
- Coast FIRE age
- Not before retirement
- Real return used
- 3.88%
- Where you stand
- Not yet: you need $328,294 more invested today to coast.
Saved scenarios
Saved in this browser only. Each column is recalculated whenever the page loads.
Milestones
| Age | Projected value | Coast target at that age |
|---|
How this is calculated
- How it works
- FIRE number = annual spending ÷ safe withdrawal rate. Real return = (1 + expected return) ÷ (1 + inflation) − 1, so 7% and 3% give 3.88%, not 4%. Coast number = FIRE number ÷ (1 + real return)^years to retirement, the compound growth the SEC's Investor.gov (opens in new window) explains. Using the real return keeps every figure in today's dollars. Monthly contributions, in today's dollars, are added at the end of each month; the coast FIRE age is the first month the balance reaches the coast target for the years then left. It exists only when the contributions would carry the balance to the full FIRE number by retirement, so the tool says "Not before retirement" when they would not.
- Not covered
- No taxes, Social Security or pension; a one-time check, not a plan.
- Privacy
- Your numbers never reach our server. The math runs on your device, inside this page.
- Corrections
- Report an error in the math to media@coinlaw.io; every report is reviewed and confirmed errors are corrected.
- Updates
- The return is now entered before inflation, with inflation as its own field, and converted to a real return exactly, so a return quoted before inflation no longer reads as a real one.
- Monthly contributions and the age at which they reach Coast FIRE, with the coast target drawn on the chart.
- The return help text no longer calls 5 percent a common planning figure.
- Feedback
- How useful was this tool?
Table of Contents
How to Use the Coast FIRE Calculator
Six inputs drive the Coast FIRE calculator. It runs in your browser, so nothing you type reaches our server. Pick one of the three “Examples” chips to load a scenario, or type your own.
- Enter your age in “Current age” and your planned retirement age in “Retirement age”. Retirement age has to come after current age and can run up to 100.
- Type the total already invested for retirement in “Invested today”. Couples can enter combined balances here and combined spending in the next field.
- Put yearly spending in “Annual spending in retirement”, in today’s dollars, as the field’s note says.
- Enter “Expected real return”, the yearly growth rate after inflation. According to the SEC, Real return is what is earned on an investment after accounting for taxes and inflation. A rate that subtracts only inflation still leaves taxes in.
- Set “Safe withdrawal rate”, the yearly draw as a share of the portfolio on the day you retire.
Results open with “Coast FIRE number (needed today)”. Next come “FIRE number at retirement”, “Your investments at retirement, no new contributions”, “Shortfall today” and “Where you stand”. A line chart tracks today’s balance by age, and a “Milestones” table lists it every five years beside the coast target for that age. “Share result” puts your inputs in a link, and “Reset” restores the defaults.
How the Coast FIRE Number Is Calculated
Coast FIRE is a variant of FIRE (financial independence, retire early). It marks the point where money already invested can grow to your retirement target with no new contributions.
Two divisions produce every result. Annual spending divided by the withdrawal rate gives the FIRE number. Dividing that by one plus the real return, raised to the years left until retirement, gives the coast number.
- FIRE number = annual spending ÷ safe withdrawal rate.
- Coast FIRE number = FIRE number ÷ (1 + real return)^(retirement age minus current age).
- Investments at retirement = invested today × (1 + real return)^years.
- Shortfall today = coast number minus invested today, or zero once you pass it.
At a 4% withdrawal rate, the FIRE number is 25 times yearly spending. That multiple is the “25x” shorthand, and 4% is the rate usually called the 4% rule. The Trinity study, covered below, works the same way. Per the AAII Journal paper, the annual dollar withdrawals are based on a first-year withdrawal rate that is a percentage of the initial portfolio value.
Growth, run backward, does the rest. On Investor.gov, the SEC’s compound interest explainer shows the forward version. Its example: if you have $100 and it earns 5% interest each year, you’ll have $105 at the end of the first year. It adds that if you never add another dime to that account, in 10 years you’ll have more than $162.
A coast number asks the reverse: how many dollars today become the FIRE number by retirement with nothing added.
How to Calculate Your Coast FIRE?
Divide yearly retirement spending by the withdrawal rate to get the FIRE number. Then divide that by one plus the real return, raised to the years until retirement. At $60,000, 4%, 5% and 30 years, that is $1,500,000.00 ÷ 4.32194, or $347,066.17.
Coast FIRE Calculator Example: Age 30 to 60 With $150,000 Invested
Opening the calculator loads its default example. The ages are 30 and 60, “Invested today” is 150,000 and “Annual spending in retirement” is 60,000. “Expected real return” is 5 and “Safe withdrawal rate” is 4. These steps reproduce its results.
- Years to retirement: 60 minus 30 leaves 30.
- FIRE number: $60,000 ÷ 0.04 is $1,500,000.00.
- Growth factor: 1.05 raised to the 30th power is 4.32194.
- Coast FIRE number: $1,500,000.00 ÷ 4.32194 is $347,066.17.
- Investments at retirement: $150,000 × 4.32194 is $648,291.36.
- Shortfall today: $347,066.17 minus $150,000 leaves $197,066.17, so “Where you stand” reads “Not yet: you need $197,066 more invested today to coast.”
As retirement nears, the “Milestones” table shows the target climbing toward the FIRE number. At 45, today’s $150,000 has grown to $311,839. The coast target for that age is $721,526, because 15 years of growth remain instead of 30.
How Much Do You Need for Coast FIRE at 30?
On the example’s inputs, a 30-year-old needs $347,066.17 invested. Spending $50,000 a year instead lowers it to $289,221.81, the same figure the “25 to 55, $50k invested” chip returns, since both span 30 years.
What Your Coast FIRE Result Means
“Coast FIRE reached” means today’s investments are projected to grow to the FIRE number by the retirement age with nothing added. Paying the bills until then still takes income; the result covers only the portfolio.
“Shortfall today” is the extra lump sum needed now. Money added later has fewer years to grow, so closing the gap later takes more than that figure.
Every year gets the same return in the projection. Real markets don’t work that way, and the Trinity authors wrote that an average-return approach “ignores the critical short-term variations in rates of return.” Taxes and fees sit outside the calculator, and the paper made the same simplification: The study did not adjust for taxes or transaction costs.
Common Mistakes When Using a Coast FIRE Calculator
- A nominal return in “Expected real return”. On the example, 7% gives a coast number of $197,050.68 against $347,066.17 at 5%. A nominal rate typed as real therefore shrinks the target by 43%.
- Spending in future dollars. The field asks for today’s dollars; inflating spending while also using a real return counts inflation twice.
- A retirement longer than the study tested. The payout periods examined were 15 years, 20 years, 25 years, and 30 years.
The 4% Rule and the Trinity Study
The study usually cited for the 4% figure is “Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable” (AAII Journal, February 1998) by Philip L. Cooley, Carl M. Hubbard and Daniel T. Walz, professors of finance at Trinity University, San Antonio, Texas.
Five mixes of stocks and bonds went into the test. The S&P 500 stood in for stocks and long-term, high-grade corporate bonds for bonds, over returns from 1926 to 1995.
Their Table 3 is the one that matches this calculator. In it, the dollar withdrawal in a given year must be increased by the inflation rate for that year. A FIRE number in today’s dollars assumes the same. Its results at the calculator’s default withdrawal rate, over 30-year payouts:
| Portfolio mix | 4% withdrawal raised with inflation, 30 years |
|---|---|
| 100% stocks | 95% |
| 75% stocks, 25% bonds | 98% |
| 50% stocks, 50% bonds | 95% |
| 25% stocks, 75% bonds | 71% |
| 100% bonds | 20% |
Source: Cooley, Hubbard and Walz, AAII Journal (February 1998), Table 3, share of 41 overlapping 30-year periods, 1926 to 1995
The paper’s summary of Table 1 reads: withdrawal rates of 3% and 4% are extremely unlikely to exhaust any portfolio of stocks and bonds during any of the payout periods shown in Table 1. That line describes a table where withdrawals stayed flat in dollars. That isn’t the table this calculator matches. Once withdrawals rose with prices, the all-bond portfolio lasted 30 years in only 20% of periods.
Its authors also cautioned that early retirees who anticipate long payout periods should plan on lower withdrawal rates. A 4% input is a planning assumption drawn from past US markets, and it carries their limits.
How Real Return and Withdrawal Rate Change the Coast FIRE Number
The real return moves the coast number sharply. With every other field at the example’s values:
| Expected real return | Growth over 30 years | Coast FIRE number |
|---|---|---|
| 3% | 2.43x | $617,980.14 |
| 4% | 3.24x | $462,478.00 |
| 5% | 4.32x | $347,066.17 |
| 6% | 5.74x | $261,165.20 |
| 7% | 7.61x | $197,050.68 |
Source: Coast FIRE Calculator outputs (FIRE number $1,500,000.00, 30 years to retirement)
Dropping from 5% to 4% raises the coast number by $115,411.83, or 33%. The SEC’s definition subtracts taxes as well as inflation. A rate that only nets out prices therefore sits at the high end of what the field asks for. The US inflation statistics show how far prices have moved in recent years.
A lower withdrawal rate works on the FIRE number instead. At 3.5%, the example’s FIRE number rises to $1,714,285.71 and the coast number to $396,647.05. At 3%, they reach $2,000,000.00 and $462,754.90, close to the 4% return row above. That one-point cut in the withdrawal rate adds $115,688.73 to the coast number, almost exactly what a one-point cut in return adds.
Social Security and the Coast FIRE Number
With no Social Security field in the calculator, its FIRE number funds every dollar of “Annual spending in retirement”. According to the Social Security Administration, you can start receiving your Social Security retirement benefits as early as age 62. Even so, you are entitled to full benefits only when you reach your full retirement age.
For people born in 1960 or later, that age is 67. Starting at 62 cuts their benefit by 30.00%.
Retiring at 60, as the pinned example does, leaves 2 years before any benefit can start. Once benefits begin, they keep pace with prices. Per the SSA’s cost-of-living adjustment (COLA) page, the purpose of the COLA is to ensure that the purchasing power of Social Security and Supplemental Security Income (SSI) benefits is not eroded by inflation. The 2026 adjustment was 2.8%, which keeps a benefit comparable with the calculator’s today’s-dollar spending.
Each $1,000 of yearly spending that another income covers lowers the FIRE number by $25,000.00 at a 4% withdrawal rate. It lowers the example’s coast number by $5,784.44. The retirement savings gap statistics track how far US savers sit from their retirement targets.
What Is a Good Coast FIRE Number?
No single coast number fits everyone. Trinity’s authors reached the same verdict on withdrawal rates: no single withdrawal rate appears appropriate for every investor. A coast number is only as sound as its spending, years, real return and withdrawal rate, and “Shortfall today” shows the distance from it.
A smaller coast number built on a higher return assumption rests on the same savings, with more hope attached. Its authors framed their own figures the same way: selection of a withdrawal rate is not a matter of contract but rather a matter of planning. Planning errors add up over decades, as the costliest retirement mistakes show.
How Long Will $750,000 Last in Retirement at 62?
At a 4% withdrawal rate, $750,000 supports a first-year withdrawal of $30,000, raised each year with inflation. The study’s inflation-adjusted table tracked a 4% start over 30 years, which reaches age 92 here. It lasted in 95% of periods for all stocks, 98% for 75% stocks and 25% bonds. A 50/50 mix held in 95% of periods, 25% stocks and 75% bonds in 71%, and all bonds in 20%.
Those are historical success rates for 1926 to 1995, and the study tested nothing longer than 30 years. Claiming Social Security at 62 as well means a benefit 30.00% below full for people born in 1960 or later.
Is there anything else my agent or I should know about this page?
Yes. The calculator runs in your browser and nothing you enter reaches our server. It assumes one steady real return every year until retirement, no new contributions and no withdrawals before then, and it rounds the years to retirement to whole years.
The FIRE number is annual spending divided by the safe withdrawal rate, and the Coast FIRE number is that figure discounted back to today at the real return, so every figure is in today’s dollars. Three things sit outside the tool: taxes and fees, Social Security or other income in retirement, and the order in which good and bad market years arrive.
CoinLaw publishes this page for information and gives no financial advice; a withdrawal rate is a planning assumption, not a promise that savings will last.
Conclusion
On the pinned example, the Coast FIRE calculator puts the coast number at $347,066.17, a $197,066.17 shortfall against $150,000 invested. Rerun it with a lower and a higher return, and a lower withdrawal rate, to see the range before trusting any one figure. The financial literacy statistics show how many US adults pass a basic financial literacy test.
