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Simple Interest Calculator

Calculate simple interest, total amount, and annual yield from a principal, rate, and time period.

Your Details

Overview

A simple interest calculator helps you estimate how much interest builds on a starting amount over time when interest is not compounded. Enter the principal, annual interest rate, and time period in years to see the total interest and final amount.

How it works

Simple interest is calculated by multiplying the principal by the annual interest rate and then by the time in years. Unlike compound interest, interest is not added to the principal for future interest calculations, so the growth stays linear over time.

How to use this calculator

  1. 1Enter the principal amount.
  2. 2Add the annual interest rate.
  3. 3Enter the time period in years.
  4. 4Review the simple interest, total amount, and yearly interest.

Example Calculation

Principal Amount

$10,000

Annual Interest Rate

5%

Time Period

3

Simple Interest

$1,500.00

With a principal of $10,000 at 5% simple interest for 3 years, the interest is $1,500, the total amount is $11,500, and the yearly interest is $500.

Frequently asked questions

What does this simple interest calculator estimate?

It estimates the total simple interest, the final amount after interest, and the amount of interest earned or owed each year.

What is the formula for simple interest?

The standard formula is principal × annual interest rate × time in years, with the rate entered as a decimal or percentage equivalent.

Does this calculator use compound interest?

No. It uses simple interest only, which means interest is calculated on the original principal and not on previously earned interest.

Can I use decimal years in the time field?

Yes. You can enter partial years such as 1.5 to represent 18 months.

Why is the result different from a bank or lender quote?

A bank or lender may include compounding, fees, different timing conventions, or other terms that are not included in this simple estimate.

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Assumptions and warnings

Assumptions

  • The interest rate stays constant for the entire period.
  • Interest is calculated using the simple interest method, not compounding.
  • The time period is entered in years and may include decimals for partial years.
  • Results are estimates and do not include taxes, fees, or penalties.

Warnings

  • This calculator provides an estimate only and is not financial advice.
  • Lenders and investment products may use different day-count conventions or terms.