Compound interest, explained with your coffee order

Compound interest means you earn returns on your returns. In year one you earn a little on what you put in. In year two you earn on what you put in plus last year's growth. Over decades, the growth starts doing more work than your deposits.

The coffee example

Say you spend $5 on coffee every working day. That's about $1,300 a year. Invest that instead at a 7% average yearly return, and after ten years you'd have roughly $18,700, of which around $5,700 is growth. After thirty years it's around $132,000, and most of that is growth, not coffee money.

This isn't an argument against coffee. It's an argument for knowing what small, repeated choices add up to, so you can decide which ones are worth it to you.

Time beats amount

Someone who invests $200 a month from 25 to 35, then stops, will often end up with more at 65 than someone who invests $200 a month from 35 to 65. The first person put in a third of the money. They just gave it more time.

Before you invest

• Have an emergency fund first, so you never have to sell investments at a bad time.
• Clear high‑interest debt. A 25% card rate cancels out any realistic investment return.
• Investments can fall as well as rise. Long-term average returns are not guaranteed, and past performance is no promise of future results.

Example amounts are scaled to typical incomes in your chosen currency. This guide is general education, not personal financial advice.