Work out the portfolio value that lets you stop adding money and still reach financial independence by your retirement age.
Spending $40,000 a year at a 4% withdrawal rate needs $1,000,000 invested. The Coast FIRE number for age 30 is $181,290, so you still need $181,290.
Spending $40,000 a year at a 4% withdrawal rate needs $1,000,000 invested. Your Coast FIRE number for age 30 is $181,290, and your portfolio is already $0 past it.
A Coast FIRE number is the balance you need invested today so that, without another contribution, it grows into your full FI number by the age you stop working. Saving stops being the plan and compounding takes over.
The arithmetic follows from spending. If you plan to live on $45,000 a year and draw 4% of your portfolio, you need $1,125,000 on the day you retire. Discounted back thirty years at a 5% real return, that target is worth roughly $260,300 today — the Coast FIRE number for a 35-year-old retiring at 65.
Reaching it changes what work has to pay for. You still need income for today's bills, but the portfolio no longer needs feeding, so a smaller salary, fewer hours or a cheaper city become live options rather than wishful thinking.
The calculator above works this out for your own numbers. If you want the long version of the idea, read what is Coast FIRE; if you would rather start from the target itself, open the FIRE number calculator.
Three steps turn a spending figure into a coasting target. They are the same three steps the coast FI calculator runs when you change an input.
Divide the spending you want in retirement by your withdrawal rate. At 4%, every $10,000 of annual spending needs $250,000 of portfolio, so $45,000 needs $1,125,000. A lower withdrawal rate raises the target in proportion: 3.5% needs about $1,285,700 and 3% needs $1,500,000.
FI number = annual spending ÷ withdrawal rate
Divide the FI number by (1 + real return) raised to the number of years between now and retirement. A real return is the growth left after inflation: a 7% nominal return with 2.5% inflation is about 4.4% real. Thirty years at 5% grows money by a factor of 4.3219, which turns $1,125,000 into $260,300. The by age page runs the same discount for other starting ages.
Coast FIRE number = FI number ÷ (1 + real return)years to retirement
Subtract your invested assets from the Coast FIRE number. A positive result is the gap you still have to close; zero or below means you are already coasting and the status reads achieved. Only the invested balance you enter is compared, so cash set aside for emergencies, home equity and expected pensions sit outside this particular calculation.
Take someone aged 35 who wants to spend $45,000 a year, expects 5% real growth and plans to retire at 65.
The same figures appear above if you enter 35, 65, 45,000 and 5%. The return assumption moves the answer a lot: at 4% real the divisor falls to 3.2434 and the Coast FIRE number rises to about $346,900, while at 6% the divisor is 5.7435 and the number drops to about $195,900.
The labels describe different end states. Only the first one leaves you with a portfolio that is still working while you keep earning.
| Type | Definition | Still need to work? | Typical withdrawal rate |
|---|---|---|---|
| Coast FIRE | The portfolio reaches full FI by retirement without further contributions. | Yes, to cover current living costs. | 4% at retirement. |
| Lean FIRE | Financial independence on a deliberately modest annual budget. | No. | 4% to 5%, because spending is small. |
| Fat FIRE | Financial independence while keeping a generous level of spending. | No. | 3% to 3.5%, to be cautious over a long retirement. |
| Barista FIRE | The portfolio covers most spending while part-time work covers the rest. | Yes, part-time, often for health cover. | 4% on the portion the portfolio funds. |
The 4% rule is a planning rule of thumb: take 4% of your portfolio in your first year of retirement, then increase that amount with inflation each year. It puts the FI number at 25 times your annual spending. It comes from historical studies of US market returns and is a starting assumption rather than a guarantee, because a long retirement or a poor sequence of returns early on can push the safe rate lower. The calculator uses whatever rate you enter, so you can test 3%, 3.5% or 5% as easily as 4%.
Yes, implicitly. The return field is a real return, meaning the growth left after inflation is taken out, and every figure on the page is in today's dollars. If you expect 7% nominal growth and 2.5% inflation, enter roughly 4.4%, which is what (1.07 ÷ 1.025) − 1 comes to. Working in today's dollars keeps the target stable, so you are not comparing a 2026 spending figure with a 2056 portfolio.
Use a number you can defend over the whole period, and keep it real. There is no correct figure, but a common planning choice for a stock-heavy portfolio is 4% to 6% real, with lower numbers for a conservative mix. The calculator does not forecast returns; it applies yours. If a small change in the rate moves the answer a long way, that is worth knowing, because it means the plan depends on market luck as much as on saving.
You can, as long as the mortgage sits inside the spending figure. A payment that ends before retirement lowers your annual spending, and the FI and Coast FIRE numbers fall with it. A mortgage still running after retirement has to be counted in spending for those years. One catch: extra principal payments are saving, but they are not invested assets, so they do not count toward the balance this calculator compares against your Coast FIRE number.
No. Financial independence means the portfolio can cover your spending now, so work becomes optional today. Coast FIRE means it will cover that spending later without further contributions, so you still need income for current living costs. Coasting is the earlier milestone and reaching FI is the later one; the financial independence calculator works out the second.
The status card reads achieved and the amount still needed drops to zero. Further contributions become optional from that point, and they shorten the time to full FI rather than keeping the plan alive. Two things are still worth checking: your spending assumption drives the whole result, and a portfolio that is past its Coast FIRE number can still fall a long way in a bad market if you start withdrawing from it before retirement.