About CoastFI
CoastFI is a small set of free calculators built for one purpose: helping people figure out their own path to financial independence, without a login, a paywall, or a sales pitch at the end.
The site started with a simple frustration — most retirement and FIRE calculators online are either buried in ads before you can see a number, tied to a specific brokerage trying to sell you something, or too generic to answer the actual question people are asking (like "when can I stop saving and just let my money grow?"). CoastFI is an attempt to fix that: fast, visual, no-signup tools that give you a straight answer from your own numbers.
What's on the site
How the calculations work
Every calculator here uses well-established, publicly documented methods from the FIRE community and retirement planning research — the 25x spending rule, real (inflation-adjusted) compound growth, and standard safe withdrawal rate assumptions like those from the Trinity Study. Every calculation runs in your browser using standard financial formulas. There's no hidden model, no black box — you can see the exact inputs driving each result, and you're always encouraged to test your own assumptions on the sliders.
Who's behind it
CoastFI is built and maintained independently, not by a bank, brokerage, or advisory firm. That independence is intentional: there's no product being upsold at the end of a calculation, and no incentive to make a number look better or worse than it is. The tradeoff is that this isn't a large team — it's a small, ongoing project, improved over time based on what's actually useful to the people who use it.
What CoastFI isn't
These calculators are educational tools, not financial advice. They simplify real-world complexity — taxes, market volatility, healthcare costs, sequence-of-returns risk, and life's general unpredictability — into a clean, understandable projection. That's useful for planning and intuition, but it isn't a substitute for a licensed financial advisor when it comes to your actual decisions.