Compound Interest Calculator
Calculate investment growth with compound interest and contributions
Enter values above to calculate
How to Use
- Enter the initial investment principal amount.
- Enter the annual interest rate (e.g., 7 for 7%).
- Enter the number of years for the investment.
- Select how often interest compounds (daily, monthly, quarterly, or annually).
- Optionally add a monthly contribution to see how regular savings grow.
About Compound Interest
The Power of Compounding
Compound interest is interest earned on both principal and previously earned interest. Over long periods, this creates exponential growth. $10,000 at 7% annually grows to $19,672 in 10 years, $38,697 in 20 years, and $76,123 in 30 years — all without adding another penny of principal.
Compound Frequency Matters
More frequent compounding yields more returns. $10,000 at 6% for 10 years: annually = $17,908, monthly = $18,194, daily = $18,221. While daily vs. monthly compounding makes little difference, the difference between annual and monthly compounding is more meaningful over longer periods.
The Rule of 72
A quick way to estimate how long it takes to double your money: divide 72 by the interest rate. At 6% annual return, money doubles in approximately 72 ÷ 6 = 12 years. At 8%, it doubles in 9 years. This rule works well for rates between 6% and 10%.
Regular Contributions Supercharge Growth
Adding even small regular contributions dramatically accelerates wealth building. $10,000 initial investment at 7% for 30 years grows to $76,123. Adding just $200/month grows the total to $311,095 — more than 4 times as much. Starting early and contributing consistently is the most powerful wealth-building strategy.
Key Features
- Supports daily, monthly, quarterly, and annual compounding frequencies
- Includes optional monthly contribution for regular savings plans
- Shows final amount, total contributions, total interest, and interest ratio
- Visual breakdown of principal vs. interest growth