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Compound Interest Calculator

Calculate compound interest with optional monthly contributions. View a year-by-year growth breakdown.

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How to compound interest calculator

  1. 1.Enter your initial principal (starting amount).
  2. 2.Set the annual interest rate as a percentage.
  3. 3.Choose the time period in years.
  4. 4.Select the compounding frequency (annually, semi-annually, quarterly, monthly, or daily).
  5. 5.Optionally enter a monthly contribution amount.
  6. 6.View the final amount, total interest earned, total contributions, and a year-by-year breakdown.

About This Tool

Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. This "interest on interest" effect causes wealth to grow exponentially over time, making it one of the most powerful concepts in personal finance and investing.

This calculator lets you model different scenarios by adjusting the principal, rate, compounding frequency, and monthly contributions. The year-by-year breakdown table shows you exactly how your money grows over time, making it easy to visualize the long-term impact of regular saving and compound growth.

Frequently Asked Questions

Simple interest is calculated only on the initial principal. Compound interest is calculated on the principal plus all previously accumulated interest, leading to exponential growth.

The more frequently interest is compounded, the more total interest you earn. Daily compounding yields slightly more than monthly, which yields more than annually. However, the differences are usually small for typical rates.

A = P(1 + r/n)^(nt), where A is the final amount, P is principal, r is the annual rate (decimal), n is the number of times compounded per year, and t is years.

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