How to use the Compound Interest Calculator
The compound interest calculator shows growth when interest is added back to the balance and also earns interest.
Open the Compound Interest Calculator →
What you need to enter
- Initial deposit ($)
- Monthly deposit ($)
- Interest rate (% / year)
- Years
- Compounds per year
The formula
Future value = P × (1 + r ÷ n)^(n × t) + deposits compounded, where n is the number of compounds per year and t the years.
Worked example
Using the default values in the calculator:
- Initial deposit ($): 5000
- Monthly deposit ($): 200
- Interest rate (% / year): 5
- Years: 10
- Compounds per year: Monthly
| Future value | $39,291.50 |
| Total deposits | $29,000.00 |
| Interest earned | $10,291.50 |
Tips for better results
- More frequent compounding helps a little, but the rate and the time matter far more.
- Add monthly deposits to see the real power of regular saving.
Common mistakes to avoid
- Comparing nominal rates with different compounding frequencies.
- Expecting the same return every year.
Please note: Calculators and guides give general estimates, not financial, tax or investment advice. Real offers depend on your lender, location and personal situation. See our Disclaimer.