Compound Interest Calculator

Calculate how your savings or investments grow over time with compound interest, including the effect of regular monthly contributions and different compounding frequencies.

Mathematical Audit

Compound Interest Formula

Compound interest is interest calculated on both your initial principal and the interest that has already accumulated. This calculator also accounts for regular monthly contributions added to the balance.

Periodic Rate = (1 + Annual Rate ÷ n)^(n ÷ 12) − 1, where n is the number of compounding periods per year
Each month: Balance = Balance × (1 + Periodic Rate) + Monthly Contribution
Total Contributions = Initial Principal + (Monthly Contribution × Number of Months)
Total Interest Earned = Final Balance − Total Contributions

Compounding frequency (daily, monthly, quarterly, or annually) affects how often interest is added to your balance, which slightly changes your effective annual yield. More frequent compounding produces a marginally higher return for the same stated annual interest rate.

Operational Guide

How to Use the Compound Interest Calculator

1

Enter your starting amount

Input the initial principal you're investing or saving.

2

Enter the interest rate and compounding frequency

Add the annual interest rate and choose how often interest compounds: daily, monthly, quarterly, or annually.

3

Add monthly contributions (optional)

If you plan to add money regularly, enter your monthly contribution amount.

4

Set your time horizon

Enter the number of years you plan to let your money grow.

5

Review your projection

See your final balance, total contributions, total interest earned, and a year-by-year growth chart.

Real-World Scenario Example

"An initial deposit of $10,000 earning 7% annual interest, compounded monthly, with $200 added each month for 20 years."

Inputs

principal:10000
annualInterestRate:7
compoundingFrequency:monthly
years:20
monthlyContribution:200

Result

After 20 years, the balance grows to $144,572.72, made up of $58,000 in total contributions and $86,572.72 in interest earned.

Important Disclaimer

This calculator provides estimates for educational purposes only and assumes a constant rate of return, which does not reflect the variability of real investments. It does not account for taxes, fees, or inflation. Consult a qualified financial advisor for guidance specific to your situation.

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