Compound Interest Calculator
Calculate compound interest growth
Investment Disclaimer
This calculator provides estimates for informational purposes only. Actual investment returns depend on market conditions, fees, and other factors. Past performance does not guarantee future results. For personalized investment advice, consult with a qualified financial advisor. TopCalculatorOnline is not responsible for any financial decisions made based on these calculations.How This Compound Interest Calculator Works
Our free Compound Interest Calculator shows you exactly how your money grows over time through the power of compounding. Enter your initial investment, monthly contributions, interest rate, and time period to see your projected future value, total interest earned, and an inflation-adjusted estimate of your real returns.
Unlike simple interest, compound interest earns "interest on interest," which means your earnings accelerate over time. This calculator supports daily, monthly, quarterly, semi-annual, and annual compounding frequencies, making it useful for savings accounts, CDs, bonds, and investment portfolios.
Compound Interest Formula Explained
The compound interest formula is:
A = P(1 + r/n)nt
- A = Final amount (principal + interest)
- P = Initial principal (starting amount)
- r = Annual interest rate (as a decimal)
- n = Number of times interest compounds per year
- t = Time in years
When you make regular monthly contributions, the future value of those contributions is calculated using the annuity formula and added to the compounded principal.
Simple vs Compound Interest
| Feature | Simple Interest | Compound Interest |
|---|---|---|
| Interest calculated on | Original principal only | Principal + accumulated interest |
| Growth pattern | Linear (steady) | Exponential (accelerating) |
| $10,000 at 7% for 10 years | $17,000 | $19,671.51 |
| $10,000 at 7% for 30 years | $31,000 | $76,122.55 |
| Best for | Short-term, simple loans | Savings, investments, long-term growth |
Example: The Power of Compounding
Investing $10,000 with $500 monthly contributions at 7% annual return compounded monthly:
| After | Total Invested | Balance | Interest Earned |
|---|---|---|---|
| 5 years | $40,000 | $47,520 | $7,520 |
| 10 years | $70,000 | $106,421 | $36,421 |
| 20 years | $130,000 | $306,752 | $176,752 |
| 30 years | $190,000 | $660,592 | $470,592 |
After 30 years, your total interest earned ($470,592) far exceeds your total contributions ($190,000) - that is the power of compound interest.
Frequently Asked Questions
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