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How to Use
- 1Enter the initial investment (principal amount).
- 2Set the annual interest rate as a percentage.
- 3Choose the compounding frequency: daily, weekly, monthly, quarterly, semi-annually, or annually.
- 4Enter the investment period in years.
- 5Optionally add a recurring monthly contribution amount.
- 6View the final balance, total interest earned, and year-by-year growth table.
About Compound Interest Calculator
The Compound Interest Calculator computes investment growth using A = P(1 + r/n)^(nt) with six compounding frequencies — daily, weekly, monthly, quarterly, semi-annually, and annually. Model any savings account, CD, or investment product with precision.
Monthly contributions use the future value of annuity formula, showing realistic growth for retirement accounts, 401(k) plans, and regular investment strategies. See how even small monthly additions compound dramatically over decades.
The year-by-year growth table breaks down balance, cumulative contributions, and interest earned for each period — making it easy to visualize the exponential curve that makes compound interest the most powerful force in personal finance.
Compare different APY rates, model the impact of starting early versus late, or estimate monthly investment needed to reach a financial goal. All calculations run locally in your browser.
Frequently Asked Questions
What compounding frequencies are available?
Six options: daily, weekly, monthly, quarterly, semi-annually, and annually. Most savings accounts compound daily or monthly.
Does it support monthly contributions?
Yes. Enter a monthly contribution amount and the calculator uses the future value of annuity formula to include regular deposits in the projection.
What is compound interest?
Compound interest is interest calculated on both the initial principal and all previously accumulated interest. This creates exponential growth over time, unlike simple interest which only applies to the principal.
Which compounding frequency gives the highest return?
Daily compounding yields slightly more than monthly, which yields more than annually — but the differences are small. What matters most is the interest rate, time horizon, and consistent contributions.
Can I use this for retirement planning?
Yes. Enter your current savings as principal, expected annual return rate, monthly contributions, and years until retirement. The growth table shows projected balance for each year.