Free retirement planning tool

Coast FIRE Calculator

Find the lump sum you need invested today to stop saving for retirement early — and see exactly when you reach Coast FI.

Coast FIRE number$—

You reach Coast FIRE at age—

Saved today vs Coast FIRE number

Portfolio growth, year by year (inflation-adjusted $)

All calculations run locally in your browser — nothing you enter is uploaded or stored on our server.

The idea

What Does Coast FIRE Mean?

Coast FIRE (often written Coast FI) is the amount of money you need invested today so that — without contributing another dollar — it grows into a full FIRE number by the time you retire. Once you hit it, you can stop saving for retirement. You still need income to cover today's bills, but your future is already paid for.

That is the difference from regular FIRE. With FIRE, you save hard and leave work entirely. With Coast FIRE, you keep working — often in a lower-stress or lower-paying job you actually like — and let compound growth do the rest.

It is built for people in their 30s and 40s who are burned out but not ready to quit. You don't need to be rich. You need to be early enough.

The math

How the Coast FIRE Calculator Works

The calculator works backwards from your full retirement target. First it finds the portfolio you need at retirement, then it discounts that target back to today using a real (inflation-adjusted) return.

The Formula

Full FI number = Annual spending ÷ Safe withdrawal rate

Real return = (1 + expected return) ÷ (1 + inflation) − 1

Coast FIRE number = Full FI number ÷ (1 + real return)^{(target retirement age − current age)}

Worked Example — age 35, $50,000 annual spending

At a 4% safe withdrawal rate, the full FI number is $50,000 ÷ 0.04 = $1,250,000. With a 7% expected return and 3% inflation, the real return is (1.07 ÷ 1.03) − 1 ≈ 3.88% per year. Grown for 30 years to age 65, that $1,250,000 target shrinks by a factor of about 3.14, so the Coast FIRE number is ≈ $398,578.

So about $398,578 invested at 35 means you never have to add another dollar. Note the inflation step — many calculators skip it and hand you a number that looks comforting but is not real.

1 · Enter your situation

Set your current age, invested assets, annual spending, and how much you save each year.

2 · Tune the assumptions

Adjust expected return, inflation, safe withdrawal rate, and target retirement age — the defaults are common planning starting points.

3 · Read the result

See your Coast FIRE number, the age you reach it, how close you are today, and the year-by-year growth chart.

Reference table

Coast FIRE Number by Age

How the Coast FIRE number changes as you age, for a saver who spends $50,000 a year and plans to retire at 65. The older you are, the fewer years the lump sum has to compound — so the required number rises.

Current age	Years until 65	Coast FIRE number
25	40	$272,300
30	35	$329,443
35	30	$398,578
40	25	$482,221
45	20	$583,417
50	15	$705,849
55	10	$853,974

Assumes $50,000 annual spending, a 4% safe withdrawal rate, a 7% expected nominal return, 3% inflation, and a target retirement age of 65. These are planning assumptions, not a guarantee — change them in the calculator above to match your own plan.

Know the difference

Coast FIRE vs FIRE vs Barista FIRE

Coast FIRE is one rung on the financial-independence ladder. Here is how it compares with the two strategies people most often confuse it with.

Strategy	Goal	What you need today	Do you keep working?	Best fit
Coast FIRE	Invest enough now that it grows to a full retirement number by your target age.	Full FI number ÷ (1 + real return)^{years until retirement}	Yes — you keep your job, but stop adding retirement savings.	Savers who want to front-load saving in their 30s and 40s without quitting work.
FIRE (fully FI)	Invested assets cover all future spending from today.	Full FI number = annual spending ÷ safe withdrawal rate.	Optional — you can stop working today if you choose.	Savers who want complete independence before traditional retirement age.
Barista FIRE	Investments cover essentials; a part-time or low-stress job covers the gap and benefits.	Usually 50–75% of the full FI number — whatever covers your baseline spending.	Part-time or flexible work for expenses, insurance, or a slower transition.	Savers who want flexibility, health benefits, or a gentler glide into retirement.

FAQ

What is a Coast FIRE number?

It is the lump sum you need invested today so that, without contributing another dollar, it grows into your full FIRE number by retirement. At $50,000 of annual spending and a 4% withdrawal rate, the full FIRE number is $1,250,000 — the Coast FIRE number is that target discounted back to today with inflation-adjusted growth.

How do I calculate my Coast FIRE number?

Divide your annual spending by your safe withdrawal rate (4% is the common starting point) to get the full FIRE number. Then discount it back by your real return — expected return minus inflation — for the number of years until your target retirement age.

What is a good Coast FIRE number at 30?

With $50,000 of annual spending, a 4% withdrawal rate, 7% expected return, 3% inflation, and retirement at 65, it is about $329,443 at 30. The same plan needs about $482,221 at 40 and $705,849 at 50 — the later you start, the higher the target, because the money has fewer years to compound.

Does the Coast FIRE calculator account for inflation?

Yes. Inflation is an explicit input (3% by default). The calculator converts the expected return into a real, inflation-adjusted return, and the chart shows your portfolio in today's dollars. Many simple calculators skip this step and overstate how little you need.

Is Coast FI the same as Coast FIRE?

Yes — Coast FI is simply the shortened form. The number, the formula, and the calculator are identical.