Financial · Live
Your FIRE number,
and how close you are to Coast.
Calculate your financial-independence number and your Coast FIRE number — the lump sum you'd need right now to reach it on growth alone. Built around a horizon-appropriate 3.5% withdrawal rate, not the traditional-retirement 4% rule.
Inputs
Your numbers
Assumptions
- Years until target age
- 35 yr
- Real return used
- 4.39%
Your FIRE number
At a 3.5% withdrawal rate on $40,000.00/yr in today's dollars.
Glide path
Coasting to your FIRE number
Field guide
FIRE number and Coast FIRE, explained.
Financial Independence, Retire Early (FIRE) reframes the traditional retirement question. Instead of "how much will I have by 65," it asks "how much do I need, period, to cover my spending indefinitely" — and then works out how far a given savings rate and timeline gets you toward that number, often well before a traditional retirement age.
The FIRE number formula
This generalizes the well-known "25× annual expenses" shortcut, which is just the special case where the withdrawal rate is 4% (since 1 / 0.04 = 25). At this calculator's default 3.5% rate, the multiple works out to roughly 28.6× instead — a larger number, reflecting the longer horizon FIRE retirees plan for.
The Coast FIRE formula
Coast FIRE asks a different question: given your target traditional-retirement age, how big a lump sum would you need right now, invested and left completely untouched, to grow into your full FIRE number by that age on compounding alone? If your current invested net worth already meets or exceeds that number, you've hit Coast FIRE — you can stop contributing and let growth finish the job.
Why this uses a real return, not the raw nominal rate
Like the sibling Retirement Calculator, this tool keeps your expected nominal return and inflation as separate inputs rather than asking for one blended "real return" guess. But your annual expenses (and therefore your FIRE number) are stated in today's dollars — so discounting a Coast FIRE target back to today has to use the real, inflation-adjusted return, not the raw nominal rate, or the today's-dollars target would be silently mismatched against a partly-inflation-driven growth rate. This calculator derives that real rate for you from the nominal return and inflation inputs.
Worked example
Age 30, target age 65, $50,000 already invested, $40,000/yr in desired spending, the calculator's own defaults (3.5% withdrawal rate, 7% nominal return, 2.5% inflation):
- FIRE number:
$40,000 / 0.035 ≈ $1,142,857 - Real return:
1.07 / 1.025 − 1 ≈ 4.39% - Years to target age:
35 - Coast FIRE number:
$1,142,857 / 1.043935 ≈ $254,036 - With
$50,000invested today, that's a real gap of roughly$204,036— still a meaningful way from Coast FIRE at these assumptions, though continued contributions (not modeled by this calculator) would close it faster.
What this calculator doesn't model
- Ongoing contributions: this tool answers "am I coasting on what I already have," not "how fast will I get there if I keep saving $X/mo" — use the Retirement Calculator for a savings-rate projection.
- Social Security: most FIRE plans deliberately exclude it as a safety margin rather than a relied-upon income source, given decades of uncertainty before it would begin.
- Healthcare before Medicare eligibility: a major real cost for early retirees leaving employer coverage years before age 65 — budget for it separately.
- Sequence-of-returns risk: a bad run of markets early in a long retirement matters more than the same bad run later — this tool uses a single fixed return, not a simulation.
Disclaimer
This calculator is a planning tool, not financial advice. Actual returns, inflation, and your own spending will vary from any fixed assumption. Use it as a directional check on how far your current assets have already gotten you, and revisit the inputs periodically as your numbers change.