Compound Interest Calculator
See how your savings grow with compound interest. Add optional monthly contributions and choose the compounding frequency.
About the Compound Interest Calculator
Our free compound interest calculator shows how your money grows over time. Enter a starting principal, annual rate, and number of years, choose how often interest compounds (annually, quarterly, monthly, or daily), and optionally add a recurring monthly contribution. The tool instantly shows your final balance, total contributions, and total interest earned — the power of compounding made clear. All math runs in your browser. Perfect for planning savings, investments, and retirement goals.
Features
- Final balance, total contributions, and interest earned
- Optional recurring monthly contributions
- Annual, quarterly, monthly, or daily compounding
- Shows the growth from compounding clearly
- Live results as you type
- 100% private — browser-only processing
How to use this tool
The Compound Interest Calculator works right in your browser — no signup, no installation. Follow these steps:
- Enter your starting principal, annual rate, and years.
- Optionally add a monthly contribution.
- Choose how often interest compounds.
- Read your final balance and total interest earned.
Frequently asked questions
What is the compound interest formula?
For a lump sum it is A = P(1 + r/n)^(nt), where P is the principal, r is the annual rate (as a decimal), n is the number of times it compounds per year, and t is the years. When you add monthly contributions, the tool compounds monthly and adds the future value of those deposits.
How does compounding frequency affect growth?
More frequent compounding earns slightly more, because interest is added to the balance more often and then itself earns interest. Daily compounding beats annual, though the difference is usually small.
Are monthly contributions before or after interest?
This calculator adds each monthly contribution and then compounds, treating deposits as ongoing. It is a close model for regular saving into an interest-bearing account.
Using the results
Use the Compound Interest Calculator to calculate from the values you enter. Check the displayed units, rounding and supported inputs when interpreting the result.