Interest Calculator – Simple & Compound Interest

Use our free Interest Calculator to instantly calculate Simple Interest and Compound Interest for savings, loans, and investments. Enter your amount, rate, and time to see how your money grows and plan smarter financial decisions online.

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Everything You Need to Know About Interest Calculators

What is an Interest Calculator?

An Interest Calculator is a financial tool that helps you calculate both Simple Interest and Compound Interest on loans, savings, or investments. By entering the principal amount, interest rate, time period, and compounding frequency, you instantly see how much interest you will earn or pay. This allows for smarter financial planning and helps you make informed decisions about borrowing, saving, or investing.

The Formulas for Simple and Compound Interest

Interest calculators use the following formulas:

Simple Interest (SI) = P × R × T / 100

Where:
P = Principal amount
R = Annual interest rate (%)
T = Time period in years

Compound Interest (CI) = P × (1 + R / n)n×T - P

Where:
P = Principal amount
R = Annual interest rate (%)
n = Number of times interest is compounded per year
T = Time period in years

How to Use the Interest Calculator

  1. Enter Principal Amount – The initial money you want to invest or borrow.
  2. Enter Interest Rate – Annual interest rate (%) offered or charged.
  3. Enter Time Period – Duration in years or months.
  4. Select Type – Choose Simple Interest or Compound Interest.
  5. Click Calculate – Instantly see results with total interest and final amount.

Once calculated, you’ll see:

  • Interest Amount: The total interest earned or paid over the selected period.
  • Final Amount (Principal + Interest): The total sum at the end of the period.
  • Monthly/Yearly Breakdown: For compound interest, see how your investment grows over time.

Practical Use Cases for Interest Calculators

Interest calculators are useful for both individuals and businesses. They can help you:

  • Plan savings accounts or fixed deposits with projected growth.
  • Understand loan repayment costs and interest accumulation.
  • Compare different compounding frequencies to maximize returns.
  • Make informed investment and borrowing decisions based on clear numbers.

Why Use an Interest Calculator?

  1. Financial Planning: Know exactly how much interest you’ll pay or earn.
  2. Compare Options: Test different interest rates, periods, and compounding frequencies.
  3. Save Money: Optimize borrowing or investment decisions to reduce interest costs or maximize gains.
  4. Transparency: Avoid surprises by seeing the real numbers upfront.