Coast FIRE Calculator

How much you need to stop saving — and whether the money lasts after you do.

Free No signup Inputs never uploaded
Your numbers
What these fields mean
Current age
Your age today.
Retirement age
Full retirement age is 67 if you were born in 1960 or later.
Current invested assets
401(k), IRA and brokerage only — exclude cash and your emergency fund.
Monthly contribution
Include your employer match. Assumed to keep up with inflation.
Expected Social Security / month
Your estimate at the age you plan to claim (ssa.gov). Claiming at 62 already reflects the permanent reduction.
Social Security claiming age
62–70. Claiming early permanently cuts the check; 70 is the maximum.
Monthly spending in retirement
In today's dollars. A 65–74 US household averages about $5,400.
Assumptions
What these assumptions mean
Growth (nominal)
Long-run nominal return, after fees.
Inflation
Long-run average, used to convert every future dollar into today's.
Withdrawal rate
The share you can take each year without running out over 30 years. Use 3.5% for longer horizons.
+ Pension
+ Future lump sum

A one-time amount you expect at a specific age — an inheritance, a home sale, a business exit. It joins your portfolio at that age and compounds from there.

Your portfolio path · age 30 → 95

Solid green — projected balance in today's purchasing power. Grey — money you put in. Dotted blue — the coast number at each age. Red — what you need by retirement. Hover for any year.

Projected balance Contributions you put in Coast number — what you need at each age What you need at retirement
$2,000$5,400

Your contributions stay constant in today's dollars.

$343,975
Your Coast FIRE number
29% funded · $243,975 to go
At $500/month you won't reach it before 67.

Coast FIRE Number by Age

The table below assumes retirement at 67, a 5% real return, and a 4% withdrawal rate. No Social Security or pension is included. These assumptions are independent of your calculator settings above — the table is a public reference, the calculator is your own numbers.

Current ageYears to 67$3,000/mo$4,000/mo$5,000/mo
2542$115,956$154,608$193,259
3037$147,992$197,323$246,653
3532$188,880$251,839$314,799
4027$241,063$321,418$401,772
4522$307,665$410,220$512,775
5017$392,667$523,556$654,445
5512$501,154$668,205$835,256
607$639,613$852,818$1,066,022
652$816,327$1,088,435$1,360,544

How to Calculate Your Coast FIRE Number

1 · Start with your retirement spending

25× your annual spending — the 4% rule. $5,400/mo → $64,800/yr → $1.62M target. Social Security is not subtracted here.

2 · Pick a retirement age and a growth rate

6% nominal − 3% inflation ≈ 2.9% real. Your money compounds at that rate until you retire.

3 · Discount backwards

Divide the target by (1 + real return) ^ years left. That's your coast number — the balance you need today to never contribute again.

Social Security is left out of the 25× target on purpose. A $2,083/month benefit shrinks the portfolio you need far more than it shrinks your spending, so the calculator does that subtraction for you.

The earlier you coast, the smaller the number — compound growth needs fewer dollars when it has more years.

What Is Coast FIRE?

Coast FIRE (also written CoastFIRE or Coast FI) is the point where your retirement accounts are big enough that, with no further contributions, they compound into a full retirement by your target age — 67 unless you set it otherwise. You stop adding to them, but you keep working, and your paycheck covers today's bills.

The word "coast" comes from riding a bike downhill: you stop pedaling, and momentum carries you the rest of the way.

The number changes once you add income. A $2,083/month Social Security benefit cuts the portfolio you need by roughly a third to a half, depending on your age — which is why the table above is labelled "no income" and the calculator asks for your benefit.

The catch most people miss: Coast FIRE says nothing about what happens after you retire. You can hit your coast number at 38 and still run out of money at 84 if you spend more than the portfolio can carry.

What the Calculator Can't Tell You

The number above answers one question: when can I stop saving? It doesn't answer the next one: what does the money do after I stop?

Two people with the same coast number can have completely different retirements. One runs dry at 79; the other still has a cushion at 95. The difference is withdrawal order, spending shape, and how much of the balance sits in tax-deferred accounts you'll be forced to tap at 73.

The full planner runs all 28 years of retirement, one row per year, and flags the year your balance hits zero.

Free Spreadsheet vs. the Full Planner

There are three things on this page. One is a calculator, one is a spreadsheet, one is a planner.

The calculator (above) — free, no email, answers "when can I stop saving."

The free spreadsheet — two tabs. Your inputs and your six results, with the arithmetic shown next to each one, plus the three levers that close the gap. Open it in Google Sheets or Excel and change the numbers yourself.

The full planner — seven tabs, $15 for the first 100 buyers and $20 after.

  1. Start here — your gap and your run-out age on one screen.
  2. Inputs — every assumption in one place, including your employer match cap and whether you actually picked your funds.
  3. Accounts — every account in one ledger, with a check when totals don't match your inputs.
  4. Accumulation — all 37 years, one row a year, in today's dollars plus nominal.
  5. Retirement — 28 years of cash flow. The year the balance hits zero is flagged red.
  6. Spending — your spending next to the BLS average for your age group.
  7. Checklist — 8 things to fix, ranked. Two of them will cost you real money.

One-time, no subscription.

The Risks of Coast FIRE

Coast FIRE doesn't fail because the math is wrong. It fails because the math gets done once and never checked again.

Coast FIRE at 25: The Early Saver

≈ $115,955

$3,000/mo spending · 42 years to 67 · 5% real

Left alone, that balance becomes about $900,000 by 67 — enough to cover $36,000 a year at a 4% withdrawal rate. Put in $50,000 today and you're already 43% of the way there.

Coast FIRE at 35: The Mid-Career Reset

≈ $251,815

$4,000/mo · 32 years · 5% real

At $150,000 invested you're 60% there. The gap is a few more years of saving, not a different life.

Coast FIRE at 45: Is It Too Late?

≈ $512,767

$5,000/mo · 22 years · 5% real

Wait until 70 and the same lifestyle needs $442,950 — three extra years of work buys a $70,000 smaller target.

What actually protects you

At 3% real, the 35-year-old's target is $466,000, not $251,815. Pick a return you'd still be comfortable with if you were wrong.

FAQ

Is Coast FIRE the same as regular FIRE?

No. Full FIRE means you have enough to stop working entirely; Coast FIRE means your retirement accounts are on track to be enough later, while you still need a paycheck today.

What is a good Coast FIRE number?

There's no single number — it depends on your retirement spending and how many years your money has to grow. A common target is 25 times annual spending: at $5,400 a month that's $64,800 a year, or $1.62 million at retirement, discounted back to today. Work yours out year by year with the Coast FIRE number by age table.

What return assumption should I use?

Most planners assume 6–7% nominal for a stock-heavy portfolio, minus 2–3% for inflation, leaving roughly 3–4% real. Our calculator defaults to 6% nominal and 3% inflation, or 2.9% real. Err conservative — optimistic returns shrink your coast number and hide the risk.

Does inflation change my number?

Only if you mix nominal and real figures, which is the most common mistake. A $1.62 million target 37 years out buys roughly what $543,000 buys today. Pick one frame — today's dollars — and stay in it.

Can I coast FIRE with a pension?

Yes — a pension lowers the number because it covers part of your retirement spending. Subtract your expected annual pension from your target spending, then apply the 25× multiplier to the remainder. A $30,000 pension against $64,800 of spending cuts the portfolio you need by about 46%, from $1.62 million to $870,000. Our calculator has a pension field — turn it on and it does this subtraction for you.

How does Social Security change the math?

It shrinks the portfolio you need, but it doesn't help in the years before you claim. The average retired-worker benefit was about $2,083 a month in 2026. Subtract it from your retirement spending, apply 25× to the gap, and remember that claiming early permanently reduces the check. The calculator does this for you — that's the "With Social Security" in the title.

What happens if the market drops right after I start coasting?

Nothing breaks unless you panic-sell. An early drop hurts more during the coast phase because you have no new contributions smoothing it out, but sequence-of-returns risk only starts when you begin withdrawing. Keep the plan, not the balance.

What about health insurance before Medicare?

It's the line item people forget. Medicare starts at 65, so retiring earlier means buying a marketplace plan yourself — price one before you commit. The full planner reserves about $165,000 for lifetime out-of-pocket medical costs.

Get the planner

These are estimates based on the assumptions you enter. Not financial advice.

The free spreadsheet takes about 10 minutes. The full planner takes an evening, and it's the one that tells you whether you'll run out at 84.

First 100 buyers pay $15. After that it's $20. One-time, no subscription.