Compound Interest Calculator

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Enter your initial investment amount in dollars
%
Enter the annual interest rate as a percentage
Enter the investment period in years
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Optional: Enter a monthly contribution amount
Select how often interest is compounded
Select when contributions are made each month

Common Savings Scenarios:

Investment Summary

Yearly Growth Schedule

Year Contributions Interest Earned Total Interest Balance

Copy these formulas into Excel or Google Sheets. Replace cell references with your values.

Future Value (Lump Sum Only)

Calculate final balance without monthly contributions

=FV(B2/12, B3*12, 0, -B1)
B1 = Principal B2 = Annual Rate (decimal, e.g., 0.07) B3 = Years

Future Value (With Monthly Contributions)

Calculate final balance with regular monthly deposits

=FV(B2/12, B3*12, -B4, -B1, 0)
B1 = Principal B2 = Annual Rate (decimal) B3 = Years B4 = Monthly Contribution Last 0 = End of period (use 1 for beginning)

Total Interest Earned

Calculate how much came from interest vs contributions

=FV(B2/12,B3*12,-B4,-B1,0) - B1 - (B4*B3*12)