What Time Does With Money

An interactive, single-page reader about compound interest: 63 short financial sentences you can rewrite by editing the numbers inside them.

Every sentence mixes two kinds of numbers: amber ones are yours to change (click and type, or nudge with ↑/↓), and green ones are recomputed live as you do. Change a $4 coffee to $7, or 20 years to 40, and the whole story updates around you.

▶ Live demo

Screenshots

What's inside

• 12 chapters: small habits, saving, investing, present value, inflation & taxes, time, starting early, reaching a goal, the big wins, investing behavior, housing, and debt.
• Editable sentences: coffee habits, monthly deposits, mortgages, credit-card minimums, salary raises, rent vs. buy, lump sum vs. dollar-cost averaging, and more.
• ƒx toggles: every sentence can show the exact formula behind its result.
• Currency picker: USD, EUR, GBP, JPY, RON and others (symbols only; amounts aren't converted).
• A live chart comparing money invested and compounding against money simply spent.
• Sources & further reading linking to the research and calculators behind the numbers.

Running it

It's one self-contained HTML file, with no build step, no server:

open compound-effect.html

Tailwind and Google Fonts are loaded from CDNs, so an internet connection is needed for full styling.

Credits

Built with the help of AI: Claude Opus and Claude Fable (Anthropic).

License

MIT, see LICENSE.