Finance

Simple & Compound Interest Calculator

Compare simple and compound growth with flexible terms and compounding frequency.

Browser-based Instant
Loading tool…

About the tool

What it does and what to expect

Compare two ways money grows

Savers, investors, students, and borrowers use interest calculations to understand growth or financing cost over time. Simple interest applies only to the original principal, while compound interest also earns or charges interest on earlier interest.

A worked example

100,000 at 10% for five years becomes 150,000 with simple interest. Compounded monthly at the same nominal rate, it grows to about 164,530 because each month’s interest joins the balance.

How it works

A simple, local workflow

  1. 1Choose simple or compound interest, then enter principal, annual rate, term, and compounding frequency.
  2. 2The calculator applies P(1+rt) for simple interest or P(1+r/n)^(nt) for compound interest.
  3. 3Compare the final balance with the original principal to see total interest earned or paid.

FAQs

Common questions

What is the difference between simple and compound interest?

Simple interest is calculated only on principal; compound interest is calculated on principal plus accumulated interest.

How does compounding frequency affect the result?

With the same nominal annual rate, more frequent compounding usually produces a slightly higher final balance.

What does principal mean?

Principal is the starting amount invested, saved, or borrowed before interest is added.

Does the calculator include regular deposits?

No. It models one starting principal without additional monthly contributions or withdrawals.

Comments & feedback

Help make this tool better

Found an edge case or have a useful idea? Send a private note to the team. Your email app opens only after you choose to send.

No comment data is stored in your browser.

Finance