Compound Interest Calculator
Principal ($), Annual rate (%), Years, and the Compound menu compute A = P(1 + r/n)^(n*t). No deposits are added during the term; that job belongs to a different calculator.
How to use
- Enter the lump sum in Principal ($). The sample is 10000.
- Enter a yearly percent in Annual rate (%). The sample is 5. The script divides by 100 to get r, then divides r by the compounding count n.
- Enter Years. The sample is 10. That value is t in the exponent n times t.
- Open Compound and choose Annually, Semi-annually, Quarterly, Monthly, or Daily. Quarterly is selected when the page loads. The counts behind those labels are 1, 2, 4, 12, and 365.
- Click Calculate. The large line is the future value in dollars and cents. The detail line is Interest earned and Principal.
When it helps
Use it to compare how often a fixed lump sum compounds when you will not add money later. Interest earned is the future value minus Principal ($). Moving Compound from Annually to Daily raises n and usually raises the balance, because the same annual rate is split into more periods.
If you also put money in every month, use the investment calculator, which always compounds monthly and has a Monthly add ($) field this page does not. For simple interest beside a once-a-year compound figure, use the interest calculator. Its compound path matches Annually here, and it has no Semi-annually, Quarterly, Monthly, or Daily choice.
Limits
There is no deposit field. A contribution during the term is ignored because it cannot be typed. Daily uses 365, not 360 and not continuous compounding. The formula is principal times (1 + annual rate divided by n) raised to n times Years. A zero rate leaves the future value equal to principal.
The form does not ask for fees, taxes, or a rate that changes after a set year. The result is arithmetic, not a bank projection and not a lender quote. Interest earned is only the growth of the original principal at the frequency you picked.
Questions
What does Quarterly actually divide by?
n is 4. Annual rate (%) becomes a decimal, that decimal is divided by 4, and the exponent is 4 times Years. Semi-annually uses 2, Monthly uses 12, Annually uses 1, and Daily uses 365.
Why is interest earned not a second balance?
The large number is already principal plus interest. Interest earned repeats the interest portion, and the detail line also repeats Principal so you can see the split. Adding those two detail figures matches the large line.
Can I add a monthly contribution here?
No. Compound has no amount-per-month control. A plan with ongoing deposits needs the investment calculator, which will not offer Annually or Daily. Keep this page for one principal and one frequency.