About CoastFIRE Hub

CoastFIRE Hub started with a calculation. The concept of Coast FIRE — reaching a savings threshold where compound interest funds the rest of retirement — is simple to state but surprisingly hard to see applied to your own numbers. Most people have no idea whether they have already crossed it.

That visibility gap is the point. Once you can see your own Coast Threshold, the picture of work changes: aggressive retirement saving stops being mandatory, and the question worth asking shifts from “how much more do I need?” to “what is my surplus actually for?”

The problem was that every FIRE calculator we found either buried the answer in walls of text, asked for 30 inputs most people do not have, or tried to sell something along the way. So we built the calculator we wished existed: one input screen, one answer, no account required, no data leaving your browser.

CoastFIRE Hub is that calculator, plus a few more tools for Barista FIRE, Fat FIRE, and comparing different FIRE paths. Every formula is open source. Every assumption is documented. Every number traces back to a primary source.

Content note: articles are researched and drafted with AI assistance, then fact-checked, edited, and verified by a human before publication. Every calculation is manually re-run and every figure is traced to its primary source (IRS, Federal Reserve, Trinity Study).

CoastFIRE Hub is a calculator toolkit built around one idea: your retirement math is simpler than the financial industry wants you to think.

The core tool is a Coast FIRE Calculator. You put in your age, current savings, annual spending, and target retirement age. It tells you your Coast FIRE number — the exact amount you need invested today so that compound interest finishes the job without another dollar of contributions from you.

There is also a Barista FIRE Calculator for part-time income scenarios, a Fat FIRE Calculator for higher spending targets, a universal FIRE Calculator, and a Coast FIRE Grid for quick lookups. More tools are added as the math warrants it.

For quick access, the CoastFIRE Hub Chrome Extension puts a fully functional Coast FIRE calculator in your browser toolbar — no accounts, no loading screens, no data leaves your device.

Every number on this site traces back to a primary source. No guessing, no rounding for convenience.

• 4% Safe Withdrawal Rate — Trinity Study (Cooley, Hubbard & Walz, 1998). A 4% withdrawal rate has historically been sustainable over 30-year periods for diversified portfolios.
• Market Returns — S&P 500 historical data: approximately 10% nominal annual returns since 1926 (source: officialdata.org).
• Inflation Rate — US CPI historical average: approximately 3% annually (source: Trading Economics).
• Real Returns — After inflation: approximately 7% annually. This is the default rate in all calculators.
• Average US Retirement Age — 61 years old (Gallup Survey, 2023).

Accuracy commitment: We review all data tables every 6 months. If you find a calculation error, email contact@coastfirehub.com and it will be corrected within 48 hours.

Last review: March 2026 | Next scheduled review: September 2026

The Coast FIRE calculation is two steps.

At $164,000 invested today, age 35, no further contributions needed. Compound interest handles the rest.

All calculators on this site use consistent assumptions: 7% real return, 4% SWR, 3% inflation, retirement age 65 in examples. Every input is adjustable.

The core calculation engine is open source: github.com/coastfirehub/fire-calculator