Money

Coast FIRE calculator

Find out how much you need invested today so that compound growth alone carries you to a full retirement, even if you never add another dollar.

Your numbers

years
years
$
In today's dollars.
$
Retirement and brokerage accounts. Leave out your home.
%
Before inflation.
%
%
4% is the classic rule of thumb.
$
Used to estimate when you hit Coast FIRE.

Results

Not financial advice. This calculator gives estimates based on the assumptions you enter. Investment returns are not guaranteed. For decisions about your own money, consider speaking with a qualified financial professional.

What Coast FIRE means

FIRE stands for "financial independence, retire early." Full FIRE is the point where your investments can pay for your life indefinitely. Coast FIRE is an earlier, gentler milestone: you have invested enough that, if you simply leave the money alone, normal market growth should turn it into your full retirement number by the age you want to retire.

Once you reach it you still need a paycheck, but only one big enough to cover today's bills. You no longer have to save for retirement, which is why many people use Coast FIRE as permission to switch to a lower-stress job, work part-time or take a career break.

How the calculator works

The calculator does three things:

  1. Finds your FIRE number. It divides your yearly retirement spending by your safe withdrawal rate. At a 4% withdrawal rate that is the same as multiplying spending by 25.
  2. Converts your return to a real return. Because spending is entered in today's dollars, growth has to be measured after inflation too. A 7% return with 3% inflation is a real return of about 3.88%, not 4%.
  3. Discounts back to today. It asks how much money, growing at that real rate for the years you have left, becomes your FIRE number. That figure is your Coast FIRE number.

If you enter a monthly contribution, the tool also steps forward month by month to show when your growing balance crosses the (also rising) Coast FIRE line, which tells you how long you need to keep saving.

The formula

FIRE number = annual spending ÷ withdrawal rate Real return r = (1 + nominal return) ÷ (1 + inflation) − 1 Coast FIRE number = FIRE number ÷ (1 + r)^(retirement age − current age)

Worked example

Maya is 30 and wants to retire at 60 spending $50,000 a year. Using a 4% withdrawal rate, her FIRE number is $50,000 ÷ 0.04 = $1,250,000.

She assumes 7% returns and 3% inflation, so her real return is 1.07 ÷ 1.03 − 1 ≈ 3.88%. Over 30 years, $1 grows to about 3.14 real dollars, so her Coast FIRE number is $1,250,000 ÷ 3.14 ≈ $398,600.

With $100,000 invested today she is about $298,600 short. If she keeps adding $2,000 a month, the calculator shows she reaches Coast FIRE in just under 17 years, at about 47. A much smaller contribution may never catch up, because the target itself keeps growing each year she waits.

Choosing sensible assumptions

  • Return: a diversified stock-heavy portfolio has historically returned roughly 6–10% a year before inflation in the US, but past results are not a promise. Using a lower figure builds in a margin of safety.
  • Inflation: 2–3% is a common long-run planning figure.
  • Withdrawal rate: the 4% rule comes from studies of 30-year retirements. If you plan to retire very early and need the money to last 40 years or more, 3.25–3.5% is more conservative.
  • Spending: include health insurance, which can be a big cost if you retire before Medicare eligibility at 65.

Small changes compound. Lowering the expected return by one percentage point can raise the Coast FIRE number by a third over a 30-year horizon, so it is worth testing a pessimistic case as well.

Frequently asked questions

What is a good Coast FIRE number?

There is no universal number. It depends on your retirement spending, how many years your money has to grow and the return you assume. A 30-year-old who wants $50,000 a year at 60 needs roughly $400,000 invested under the example assumptions above, while a 45-year-old with the same goal needs far more because there is less time for growth.

Is Coast FIRE the same as Barista FIRE?

No. Coast FIRE means your retirement savings are complete and you only work to cover current expenses. Barista FIRE usually means you have already left full-time work and use part-time income to fill a gap while your portfolio covers the rest.

Should I stop investing once I hit Coast FIRE?

You can, but you do not have to. Many people keep saving a little to build a buffer against weak market returns, or to reach full FIRE earlier. Coast FIRE simply means further saving is optional.

Why does the calculator use a real return?

Your spending is entered in today's dollars. Measuring growth after inflation keeps both sides of the equation in the same units, so the result is not inflated by price rises.

Does this include Social Security or a pension?

No. If you expect guaranteed income in retirement, subtract it from your yearly spending before you enter it. That lowers both your FIRE and Coast FIRE numbers.

Last reviewed November 2026. Spotted an error? Tell us.