Personal finance, with the arithmetic shown.
Guides and calculators for people on ordinary salaries, written separately for US and German rules. Every figure comes with the assumptions behind it, so you can check it.
| Saved each month | $300 |
|---|---|
| Years | 30 |
| Paid in | $108,000 |
| Fund at 0.2% a year | $351,871 |
| Fund at 0.7% a year | $319,241 |
| Cost of the higher fee | $32,630 |
7% return before fees, compounded monthly. No taxes.
Change the numbersStart with these
All 82 guides
Foundations8 minFreeBudgeting methodsFour ways to set spending limits, and how to tell which one survives a bad month.
Investing7 minFreeETFs vs mutual fundsSame index, two wrappers. Where the real difference is, and why index vs active matters more.
Investing6 minFreeCompound interestWhy the early years look boring, and where the growth happens.The order we would do it in
Most money advice is correct and arrives in the wrong sequence. This is the sequence.
- Know where the salary goesA budget you can keep in a bad month, not a perfect one.
- Build a cash bufferThree to six months of essential spending, somewhere boring.
- Clear expensive debtAnything above roughly 8% APR goes before investing.
- Invest in broad index fundsLow fees, automatic contributions, left alone.
- Use the tax-advantaged accountsTake the employer match first, then the rest of the allowance.
Calculators
Free, no account needed. Each row shows an example input and what comes out.
| Calculator | Example | Result |
|---|---|---|
| Budget planner | $3,000 take-home, split 50/30/20 | $1,500 / $900 / $600 |
| ETF cost comparison | $300 a month for 25 years, 0.2% vs 1% | $27,571 lost to fees |
| Debt payoff | $8,000 at 19.9% APR, $250 a month | 46 months, $3,498 interest |
| Retirement | $400 a month from 30 to 67 at 5% | $512,201, about $20,488 a year |
| Net worth tracker | Assets minus debts, one entry a month | The change since last month |
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Educational content only. Not personal financial advice.