Compound Interest Calculator
Start with an amount, add optional monthly contributions, pick a rate and time — see how much your money grows and how much of it is interest.
📈 Your savings plan
Compounding assumed monthly — the most common schedule for savings accounts and investments.
Future value
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How this compound interest calculator works
Each month, your balance earns the annual rate divided by 12, then your monthly contribution is added. Repeated over years, growth stacks on growth — that's compounding. The table shows the balance, what you put in, and what interest added, year by year.
Common uses
- Project retirement or long-term savings at 5–8% average returns.
- See how much a savings account rate actually earns over a decade.
- Compare "invest vs repay the mortgage" using the loan payment calculator.
- Estimate the tax hit when you withdraw with the capital gains tax calculator.
For general understanding only — not financial advice. Returns are assumed constant; real investments fluctuate.