When to use Compound Interest Calculator
You're 32, trying to decide whether to move $10,000 from a 0.5% savings account into an index fund averaging 7% annually — and you want to see the 30-year difference side by side. Enter the principal, the annual rate, the compounding frequency (daily, monthly, or annual), and an optional monthly contribution, and a year-by-year balance table appears. The chart makes viscerally clear how much of the ending balance is interest earned rather than money you deposited — compounding daily versus annually on $10,000 at 7% over 30 years produces a measurable gap. Useful for comparing HYSA rates, modeling 401(k) contribution increases, or understanding how a debt grows when you only pay the minimum. All calculations happen in your browser tab.
- Compare daily vs annual compounding on a $10k savings deposit
- Model a $200/month 401k contribution over 30 years
- See how a credit card balance grows when only paying minimums