Compound Interest Calculator — Growth Chart & Contributions
Compound interest is interest earned on both your initial deposit and previously earned interest — creating a snowball effect that accelerates your savings growth. Our free calculator shows you exactly how your money will grow over any time period with customizable compounding frequency and monthly contributions. Enter your starting amount, monthly contribution, interest rate, and time horizon to see a detailed breakdown with a year-by-year balance table.
Compounding frequency is the setting most people skip and it is worth a minute of attention: the same 6% compounded monthly rather than annually adds roughly a quarter of a percent to your effective rate, and over thirty years that gap is real money. The chart separates what you put in from what the interest produced, which is the useful comparison — for most long horizons the interest eventually contributes more than the deposits, and seeing the year that crossover happens is more persuasive than any final total.
How to use Compound Interest Calculator
- Enter your initial deposit amount.
- Add a monthly contribution (optional).
- Set the annual interest rate and compounding frequency.
- Choose your investment period in years to see the growth breakdown.
Features
- Initial deposit and monthly contributions — Model realistic savings scenarios.
- Compounding frequency — Daily, monthly, quarterly, or annually.
- Year-by-year balance table — See your balance grow year by year.
- Contributions vs interest breakdown — See how much comes from deposits vs earned interest.
- Adjustable investment period — From 1 to 50 years.
- 100% browser-based — No data sent to any server.
Frequently Asked Questions
Can I use this as a high-yield savings account (HYSA) calculator?
Yes. Enter your starting balance and monthly deposit. If the bank quotes an APY, enter it with annual compounding, because APY already includes the effect of compounding. If it quotes an interest rate (APR), enter that with daily or monthly compounding to match how the bank credits interest.
How does compound interest differ from simple interest?
Simple interest is calculated only on the principal amount. Compound interest is calculated on the principal plus all accumulated interest. Over time, compound interest produces significantly larger returns because you earn interest on your interest.
How often should interest be compounded?
More frequent compounding produces slightly higher returns. Daily compounding yields more than monthly, which yields more than annually. The difference becomes more significant with larger amounts and longer time periods. Our calculator lets you compare all options.
How much will $10,000 grow in 10 years?
It depends on the interest rate and compounding frequency. At 7% annual return compounded monthly, $10,000 grows to approximately $20,097 in 10 years. Add monthly contributions of $200 and it reaches approximately $54,696. Use our calculator to model your specific scenario.
Does it matter whether interest compounds monthly or annually?
It does, though less than the rate itself. At 6%, monthly compounding gives an effective annual rate of about 6.17% against 6.00% compounded annually. On a 30-year balance that difference compounds into a noticeable gap. Savings accounts usually compound daily or monthly; bonds and some fixed deposits compound annually or semi-annually.
Should I invest a lump sum or contribute monthly?
Mathematically a lump sum usually wins, because the money starts compounding sooner. Monthly contributions win on practicality and on smoothing out the risk of investing everything on a bad day. Run both in the calculator with your own numbers — the gap is often smaller than people expect over a long horizon.