Free FIRE calculators & FI guides
FIRE calculators and FI guides
Plain-English guides to the math behind financial independence: the FI-number formula, the 4% rule, sequence-of-returns risk, and the whole family of FIRE variants. Read a guide to understand the concept, then jump to the matching interactive calculator to run your own numbers. Every calculator runs entirely in your browser — your numbers never leave your device, and there's no signup.
Guides
Articles that explain the concepts and sources behind every number — read these first.
- What is your FI number? The formula, the 4% rule, and worked examples behind every number here.
- The 4% rule & safe withdrawal rate Where the 4% rule comes from, when it breaks, and safer rates for early retirement.
- Sequence-of-returns risk Why the order of your returns — not just the average — decides how long money lasts.
- Types of FIRE Lean, Barista, Coast, and Fat FIRE — the same math with different target spend.
- FI number by U.S. state (2026) What FIRE costs in every state, from ~$1.71M in Arkansas to ~$2.17M in California.
- Salary needed to buy a house, by state (2026) What a typical home takes in all 50 states — June 2026 Zillow values, real state tax rates.
- Rent vs. buy salary, by state (2026) The salary to rent a 2BR vs. buy the typical home — and the gap, ranked.
- How long to save a down payment, by state (2026) Years to 20% down at the average American saving rate vs. a disciplined 10% — ranked.
- Best FI & FIRE planning tools (2026) An honest comparison of ProjectionLab, Boldin, Empower, spreadsheets, and more.
Interactive calculators
Not articles — these are the free, no-signup tools that run the numbers for you.
- FI Number Calculator Your core FI number and a rough date to financial independence — free, no signup.
- Coast FIRE Calculator The smaller amount that grows to full FI on its own — stop saving, keep coasting.
- Barista FIRE Calculator How steady part-time income shrinks the portfolio you need to semi-retire.
- Lean FIRE Calculator Reach financial independence sooner on a deliberately frugal budget.
- Fat FIRE Calculator Fund a no-compromises, higher-spending early retirement.
- Chubby FIRE Calculator The comfortable middle band between lean and fat FIRE.
- ACA Subsidy Calculator Estimate the ACA health-insurance subsidy for an early-retirement year (2026 plan year).
- Career Change Calculator What a pay cut really costs you — the change to your FI date, in years.
These are interactive calculators, not guides. See every calculator in one place on the Calculators page.
Turn a number into a plan
A single number is where planning starts. When you want the full picture — the 4% debate stress-tested with a Monte Carlo chance of success, taxes, and a plan you can track — start with the free FI calculator or read what a FI number is.