Calculate the long-term compound growth of your investments with our free Compound Interest Calculator. Project future balance, principal contribution, and net interest earned across custom time horizons and compounding frequencies (annual, monthly, daily) with 100% offline privacy.
Type your starting deposit amount, annual interest rate percentage, and duration in years.
Choose Annually, Monthly, or Daily compounding from the frequency dropdown.
Instantly inspect your future total balance, interest earned, and principal vs interest bar chart.
All interest calculations run locally inside browser JS memory. No financial figures are transmitted to external servers.
Input adjustments update the future value, net interest earned, and visual breakdown bars in real time.
Calculates precise compound returns using standard financial formulas (\(A = P(1 + r/n)^{nt}\)) with flexible compounding frequencies.
Compound Interest differs fundamentally from simple interest because interest earned during each period is added to the principal balance, becoming part of the base for subsequent interest calculations. This creates an exponential growth trajectory described by the formula: \(A = P \left(1 + \frac{r}{n}\right)^{nt}\).
Where A is future value, P is initial principal, r is annual interest rate, n is compounding frequency per year (\(1\) for annual, \(12\) for monthly, \(365\) for daily), and t is time in years. Net compound interest earned is derived as \(I = A - P\).
To estimate doubling time at a given annual return rate, investors often use the Rule of 72: \(\text{Years to Double} \approx \frac{72}{r \times 100}\) (e.g. at 6% annual rate, \(72 / 6 = 12 \text{ years}\)).