Frequently Asked Questions
What is compound interest?
Compound interest is interest earned on both principal and accumulated interest. Unlike simple interest, it grows exponentially. The Rule of 72: divide 72 by the interest rate to find how many years to double your money. At 8% interest: 72/8 = 9 years to double.
How often does interest compound in US accounts?
High-yield savings accounts and CDs typically compound daily or monthly. S&P 500 index funds compound continuously as dividends are reinvested. Daily compounding earns slightly more than monthly — on $10,000 at 5% for 10 years, daily compounding earns about $50 more than monthly.
What is the best compound interest account in the USA?
Top options: High-yield savings accounts (4-5% APY, FDIC insured), Treasury I-Bonds (inflation-adjusted, 5%+), S&P 500 index funds (historical ~10%/yr), Roth IRA with index funds (tax-free growth), 401(k) with employer match (instant 50-100% return on matched amount).