Interest Calculators

MiniWebtool’s Compound Interest Calculator projects a principal at a stated annual rate and compounding frequency over time. The result separates starting money from interest and shows the accumulating balance year by year.

Explore the continuous-compounding model in MiniWebtool’s Continuous Compounding Calculator. Principal, annual rate, and time determine Peʳᵗ and interest earned, with growth charts and a comparison to periodic compounding at the same rate.

MiniWebtool’s Doubling Time Calculator relates a constant growth rate to the time needed for a quantity to double. Solve for time or the required rate, with optional starting-value context and a growth visualization.

MiniWebtool’s Rule of 72 Calculator estimates investment doubling time from a growth rate, or the rate needed for a target time. Compare this shortcut with compound-growth calculations and related approximation rules.

Enter principal, annual rate and a duration in days, weeks, months or years into MiniWebtool’s Simple Interest Calculator to calculate simple interest and the total principal plus interest.