Compound Interest Calculator
Calculate investment balance growth with flexible compounding schedules and recurring deposit options.
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This compound interest calculator projects the growth of your savings or investment balance across any chosen time horizon. Enter your initial principal, expected annual interest rate, and target duration in years to evaluate how interest accumulates over time. You can customize the compounding schedule by choosing daily, monthly, quarterly, semiannual, or annual intervals to match your specific financial account terms. To model ongoing savings habits, add regular recurring contributions on a monthly, quarterly, annual, or lump-sum schedule. Negative entries for principal or interest rate are treated as zero, and durations under one year are set to a one-year minimum. If an unrecognized compounding schedule or contribution frequency is selected, the tool uses annual compounding and monthly contributions by default. All computed future balances, earned interest totals, and contribution subtotals are rounded to two decimal places, providing clean figures for long-term retirement planning, education funds, or general investment projections.
Instructions
- Enter your starting investment balance in the Principal field.
- Specify your expected annual interest rate as a percentage.
- Enter the investment duration in years.
- Select your preferred compounding frequency from the Compound dropdown menu.
- Optionally enter recurring deposit amounts in the Contributions field and choose the contribution frequency.
- Click Run to see your estimated ending balance and total interest earned.
Examples
- Initial deposit of $5,000 at a 6% annual rate for 10 years with monthly compounding results in an ending balance of $9,096.98.
- Starting with $10,000 at 7% annual interest over 20 years with annual compounding and an added $200 monthly deposit grows to $139,478.47.
FAQ
How does compounding frequency impact investment returns?
More frequent compounding, such as daily or monthly intervals, generates slightly higher returns than annual compounding because interest is credited and begins earning interest sooner.
What happens if a negative principal or interest rate is entered?
If you enter a negative value for the principal or interest rate, the tool treats those entries as zero so your projection remains valid.
What is the minimum investment period supported by the tool?
The calculator uses durations rounded to whole years, with a minimum period of one year.
How are recurring deposits calculated over time?
When you specify a contribution amount greater than zero, the selected monthly, quarterly, annual, or lump-sum deposit schedule is factored directly into the growth balance alongside your initial principal.