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Stop contributing — let compounding finish the nest egg

Coast FIRE Calculator

Coast FIRE asks how large your portfolio must be today so that, with no further contributions, growth alone reaches a traditional FIRE nest egg by retirement. Nest egg = annual spend ÷ withdrawal rate; coast number = nest egg ÷ (1 + real return)^years.

Today’s dollars for the lifestyle you want when you stop working.

Common planning starting point is 4%. Lower is more conservative.

Years of growth with no new contributions in the Coast scenario.

Return after inflation. A long-term stock/bond mix is often modeled in the mid single digits.

Investable assets you would leave invested. Leave 0 to ignore.

Coast number (needed today)

$376,889

Full FIRE nest egg
$1,000,000
Still needed to coast
$226,889

How Coast FIRE is calculated

  1. Full FIRE nest egg = annual spending ÷ (withdrawal rate as a decimal). At 4%, that is spend × 25.
  2. Pick years until you plan to stop contributing and an expected real (after-inflation) return.
  3. Coast number today = FIRE nest egg ÷ (1 + real return)^years.
  4. If your current portfolio is at or above the coast number, you have “coasted” under these assumptions.
  5. Gap = coast number − current portfolio (when still short).

Returns, inflation and spending are uncertain. Sequence of returns and fees can change outcomes a lot.

When this planning view helps

  • Checking whether you can pause 401(k) contributions and still hit a date
  • Comparing 3.5% vs 4% withdrawal rate sensitivity on the same spend
  • Seeing the gap between today’s balance and the coast threshold
  • Teaching the Coast FIRE identity without a spreadsheet

Assumptions to watch

  • Mixing nominal returns with today’s-dollar spending (inflation double-count)
  • Treating 4% as a guarantee rather than a planning starting point
  • Ignoring fees, taxes and sequence risk after you “coast”
  • Counting house equity as investable portfolio when it will not be sold

Worked examples

Twenty years to coast

$40,000 spending, 4% withdrawal, 20 years, 5% real return, $150,000 saved.

$376,889 · ≈ $1,000,000

Already at full FIRE math

$50,000 spending, 4% SWR, 0 years left, $1.3M portfolio.

$1,250,000 · ≈ $1,250,000

Conservative withdrawal rate

$40,000 spending, 3.5% SWR, 15 years, 4% real return, $0 saved.

$634,588 · ≈ $1,142,857

Frequently asked questions

What is Coast FIRE?

It is the idea that once your invested nest egg is large enough, investment growth alone can fund retirement by a chosen date even if you never contribute again. You may still work to cover current living costs.

Is 4% a guaranteed safe withdrawal rate?

No. The “4% rule” is a historical planning rule of thumb from retirement research, not a guarantee. Markets, fees, taxes and spending flexibility all matter.

Should I use nominal or real return?

This calculator uses real return and spending in today’s dollars so inflation is not double-counted. If you prefer nominal figures, keep spending and returns both nominal.

Does this include Social Security or pensions?

No. Reduce the annual spending input by expected guaranteed income if you want a rough adjustment, or keep spending gross and treat pensions separately.

Sources and updates

Last reviewed .

  • Coast FIRE identity – coast = (spend / SWR) / (1 + r)^n. Educational planning identity widely used in FIRE communities.
  • Withdrawal-rate research context – The common 4% starting point relates to historical safe-withdrawal studies; it is not personalized advice.

Educational planning tool only. Not investment, tax or financial advice. Past returns do not predict future results.

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