About CoastMath

CoastMath is an independent, advertising-supported website. CoastMath turns the arithmetic behind Coast FIRE and financial independence into clear browser calculators, with every assumption visible, so people can test their own numbers instead of trusting a single headline figure.

What we publish

Five calculators — Coast FIRE, FIRE number, years to financial independence by savings rate, Barista FIRE, and a retirement withdrawal (how long will my money last) calculator — plus original guides. We do not manage money, sell investments or give personal advice.

How we research

We base explanations on primary or well-documented sources that we checked when this edition was built: IRS pages on contribution limits and early-distribution rules, IRS Publication 590-B, HealthCare.gov and Medicare.gov, the SEC’s Investor.gov, and Morningstar’s published safe-withdrawal-rate research. We summarise in our own words and link the source on each page. NestEgg on dollarfinch.com covers 401(k) match and Roth decisions; CoastMath focuses on FIRE targets and timelines. Every figure that comes from a third party is linked at the bottom of the page where it is used, and every page shows when it was last reviewed. If a carrier, retailer or organisation changes its published information, the official source wins over anything on this site.

How the tools work

Calculations run in your browser from what you enter. Nothing is uploaded to CoastMath. Results use a constant real return, which real markets never deliver; treat them as planning sketches.

How we make money

CoastMath shows advertising (Google AdSense) and does not accept payment from insurers, brokers, banks or any company in exchange for coverage in our guides. We do not sell leads, and we do not sell or recommend any specific insurance policy or financial product.

Corrections

If you spot an error, tell us through the contact page. We correct factual mistakes quickly and update the “last updated” date when we do.