Finance tool
FIRE calculator
Enter your savings, expenses, and expected return — see your FI number, age at financial independence, and lean vs fat FIRE targets live.
Start with the free manual tool. If you want the real document view after that, analyze a statement PDF.
Free tool
Run the FIRE math on your actual numbers
Plug in your actual numbers. The calculator solves for years to FI, age at FI, total FI number, and current progress — plus lean and fat FIRE thresholds for comparison.
FIRE inputs
Based on the 4% safe withdrawal rule (or your custom rate). Assumes stable inflation-adjusted returns.
Retirement + brokerage + HYSA — everything invested or liquid.
What you spend now, adjusted for expected retirement lifestyle.
How much you invest or save each month.
Long-term real (inflation-adjusted) return. S&P historical is ~7%.
4% is the standard Trinity study. Conservative use 3-3.5%.
In 17y 10m at 7% real return. FI number is $1,350,000 (25× annual expenses at 4% withdrawal).
25× annual expenses.
214 months.
Strong.
Of total FI number saved today.
Lean FIRE: $945,000 — live on 70% of current expenses.
Regular FIRE: $1,350,000 — maintain current expenses.
Fat FIRE: $2,025,000 — live on 150% of current expenses for more lifestyle.
Natural next step
Real numbers beat guesses
The FIRE math is only as good as the 'monthly expenses' and 'monthly savings' inputs. Upload your bank statement to get the real numbers from the past 3-6 months — not your best-case guess.
What it gives you
Fast enough for a first pass
Each tool is intentionally narrow. The job here is a clean estimate, not a fake replacement for a full statement analysis.
4% rule math, configurable
Uses the 4% safe withdrawal rule from the Trinity Study — adjustable for more conservative 3% or aggressive 5% planning.
Lean / regular / fat side-by-side
Shows lean, regular, and fat FIRE thresholds simultaneously — no need to rerun for each scenario.
Savings rate + progress
Surfaces implied savings rate and current progress percentage — the two numbers that most predict FI date.
When it's useful
A FIRE simulator built on the 4% rule and monthly compound returns. Runs entirely in the browser.
Anyone exploring early retirement
Shows exactly how many years off your desired retirement age a higher savings rate buys you — the most visceral argument for increasing savings.
Savers comparing lifestyles
Run once at current expenses, then once at 70% (lean) or 150% (fat) to see how lifestyle choice changes years to FI.
Career switchers weighing a pay cut
If a career change cuts income but lowers expenses, re-run with new numbers to see the net effect on FI date.
People reviewing their savings rate
The tool surfaces your implied savings rate — one of the strongest predictors of years to FI. Higher savings rate matters more than higher return.
Deeper context
Why savings rate matters more than return rate
The counter-intuitive truth behind early retirement math.
A 50% savings rate gets you to FI in ~17 years
Even at 5% returns, saving half your take-home pay compounds to FI in under 20 years. At 10% savings, it takes 50+ years. Savings rate compresses timelines more than any realistic change in investment returns.
Higher savings = lower target simultaneously
Living on less means your FI number shrinks AND your monthly contribution grows. Both effects compound. Shaving $1,000/month off expenses drops your FI number by $300,000 at a 4% rate — while also adding $1,000/month to investments.
Return rate matters at the margins, not the mean
Swapping 6% for 8% real return saves you 2-4 years over a 20-year path. Swapping 20% savings for 40% savings saves you 15+ years. Focus on the bigger lever first.
Deeper context
Common mistakes this calculator surfaces
FIRE planning fails for a few predictable reasons.
Using aspirational expenses, not real ones
If you enter $3,500/month expenses but actually spend $5,200, the calc will give you a date you'll miss by 5+ years. Use real statement data.
Forgetting taxes and health care
The 4% rule includes US inflation but NOT US health insurance premiums if you're retiring before Medicare at 65. For US early retirees, add ~$500-1,500/month for pre-65 health insurance to your expenses.
Assuming constant contributions forever
Life happens — career breaks, kids, sabbaticals. The calculator assumes steady contributions; your real path will have gaps. Build in a buffer by retiring on a lower safe withdrawal rate (3.5% instead of 4%).
FAQ