Compound Interest: The Good, The Bad, and The Ugly
Understanding the force that builds wealth and destroys it
3 min read
554 words
3/10/2026
Einstein reportedly called compound interest the "eighth wonder of the world." I'm not sure he said that, but the principle is sound: compound interest can make you rich or keep you poor, depending on which side of it you're on. Let me explain how it actually works.
How to Use
Enter your principal, interest rate, time period, and compounding frequency. The calculator shows how your money grows. The key insight: more frequent compounding = more growth. Daily beats monthly, which beats annually. But here's what matters: compound interest works both ways.
Pro Tips
Tip 1: Start early. ,000 at 7% for 40 years = 4,974. For 20 years = ,869. Time is your biggest ally. Tip 2: High-interest debt is compound interest working against you. Credit cards at 20% APR will double your debt in 3.5 years. Tip 3: Don't interrupt the compounding. Let dividends reinvest.
Common Mistakes to Avoid
The biggest mistake: underestimating the power of time. A 25-year-old investing 00/month at 7% will have more at 65 than a 35-year-old investing 00/month. Another error: ignoring fees. A 1% fee might sound small, but over 30 years, it can eat 25% of your returns.