MoneyMath

The math of money,
made simple.

Free calculators for FIRE, savings, net worth, and the real cost of the things you spend on. Run privately in your browser. No accounts, no tracking — just honest math, plainly explained.

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FIRE family

When can you stop working?

Four flavors of financial independence. Same math, different lifestyle bets.

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Income & Wealth

What you make. What you keep.

Your real hourly rate, what to charge clients, what you're worth, and what the IRS takes.

Selling & Reseller

What marketplaces actually take.

eBay, Etsy, Mercari, Poshmark — every fee on a sale, your net payout, and the breakeven price.

Investing

What money does over time.

Compounding, annualized returns, and inflation — the three forces that decide what your money becomes.

Debt & Costs

What things actually cost.

Money flowing out — over the full term, not the sticker. Loans, recurring obligations, big purchases.

One short note a week.

A new calculator, a back-of-the-envelope tear-down of a money decision, or a reading list. No fluff.

Free, weekly, unsubscribe anytime.