Compound Interest Calculator

Tool Guide

About This Tool

Compound Interest Calculator shows how your principal grows at a fixed annual rate over time — making the power of compounding visible with a growth curve chart. Also supports regular additional contributions (DCA mode).

Core Features

1. Compound interest: Calculate final amount and total gain with annual, monthly, or daily compounding.

2. Growth chart: Visualizes the compound growth curve and compares different rates and durations.

3. DCA mode: Calculates results when you add a fixed amount periodically (dollar-cost averaging).

How to Use

Step 1: Enter the initial principal, annual rate, and investment duration.

Step 2: Select compounding frequency (annual/monthly).

Step 3: View the final amount, total gain, and growth chart.

Use Cases

Investment planning: Estimate expected returns on long-term stock, fund, or savings investments.

Education fund: Calculate how much you need to save now to reach a target amount by a given date.

Retirement planning: Model how different investment strategies grow into retirement savings.

FAQ

Q: What is the difference between compound and simple interest?

A: Simple interest applies only to the principal; compound interest applies to principal plus accumulated interest — producing dramatically larger totals over time (Einstein reportedly called it the eighth wonder of the world).

Q: What is the Rule of 72?

A: Divide 72 by the annual rate to estimate how many years it takes to double your money. At 8% per year: 72 ÷ 8 = ~9 years.