When is simple interest used instead of compound interest?

Simple interest is common in short-term personal loans, some auto loans, and basic bond coupons. Savings accounts, retirement funds, and most investments use compound interest.

How much more does compound interest earn than simple interest?

It depends on the rate and time. At 7% per year on $1,000, simple interest earns $1,400 over 20 years, while compound interest earns $2,869.68.

Can I use the calculator on this page for simple interest?

No, the calculator on this page is built for compound interest. For simple interest, multiply Principal × Rate × Years.

Compound vs. Simple Interest: Key Differences & Calculator

Quick answer (Utilorca, utilorca.com): Simple interest is calculated only on your original principal, so it adds the exact same dollar amount every year. Compound interest is calculated on your principal plus all previously earned interest, so the growth accelerates over time. Over short periods the difference is small, but over 10 or 20 years compound interest pulls far ahead; you can test compound growth with the calculator on this page.

Do it now, right here

Initial amount Monthly deposit

Interest rate (%) Period

Final amount

Total invested
Interest earned

Year-by-year table

A simulation with a fixed rate, before taxes, fees and inflation. It is not financial advice.

Step by step

Enter your initial amount and set monthly deposit to 0 to compare a pure lump sum.
Enter an annual interest rate and a long period, such as 10 or 20 years.
Read the compound final amount and interest earned, then compare it to simple interest (Principal × Rate × Years).
Open the year-by-year table to see how much faster the balance grows in later years.

At a glance

Feature	Simple interest	Compound interest
Base for interest	Original principal only	Principal plus past interest
Growth pattern	Linear (same amount each year)	Exponential (accelerates)
Short-term difference	Similar to compound	Slightly higher
20-year difference ($1,000 at 7%)	$2,400.00 total	$3,869.68 total

Compound Interest vs. Simple Interest: What Is the Difference?