UlvixorCompound Interest Calculator
Calculate how your money grows with compound interest over time, including optional periodic contributions. Choose the compounding frequency (annual, monthly, or daily) and see your final balance, total contributed, and interest earned.
How it works
- Enter the initial capital you want to invest or save.
- Enter the annual interest rate (%) offered by the financial product.
- Select the compounding frequency: annual, monthly, or daily.
- Enter the term in years and, if you'd like, an additional periodic contribution for each compounding period.
- The calculator shows the final balance, the total contributed (principal + contributions), and the total interest earned.
Use cases
- Projecting the growth of a savings or investment account over the long term.
- Comparing the effect of different compounding frequencies on the same principal.
- Estimating how much you need to contribute monthly to reach a savings goal.
- Visually understanding the power of compound interest versus simple interest.
Use cases
- Projecting the growth of a savings or investment account over the long term.
- Comparing the effect of different compounding frequencies on the same principal.
- Estimating how much you need to contribute monthly to reach a savings goal.
- Visually understanding the power of compound interest versus simple interest.
Common mistakes
- Confusing simple interest with compound interest, expecting the balance to grow linearly instead of at an accelerating rate.The calculator applies the compound interest formula, where each period also earns interest on the interest accumulated so far, not just on the initial principal.
- Entering a periodic contribution meant for a different frequency than the compounding you selected, for example a monthly amount with annual compounding selected.The contribution you enter is added at every compounding period you choose (annual, monthly, or daily). Adjust the contribution amount to match the selected frequency so the result reflects what you actually plan to contribute.
- Using the annual interest rate as-is for every period, without adjusting it to the compounding frequency.The tool automatically divides the annual rate by the number of periods per year (12 for monthly, 365 for daily) before applying it.
Frequently asked questions
It's interest calculated not only on the initial principal, but also on the interest accumulated in previous periods, which makes the balance grow at an accelerating rate over time.
It uses the compound annuity formula: FV = P(1+r)^n + C × (((1+r)^n − 1) / r), where P is the initial principal, r is the rate per period, n is the total number of periods, and C is the periodic contribution added at the end of each period.
Yes. To keep the calculation consistent, the contribution you enter is added at each selected compounding period (for example, if you choose monthly compounding, the contribution is added every month).
The more frequent the compounding, the more often interest is calculated and added to the balance each year, which produces a slightly higher final balance for the same nominal annual rate.
Alternatives
In Excel or Google Sheets, the FV function calculates the balance with compound interest and contributions, though you have to get the signs and number of periods right. This calculator simplifies that: you choose the compounding frequency and see the final balance, total contributed, and interest earned without adjusting formulas by hand.