Interest Calculator (Simple & Compound)

Introduction

Interest describes how money grows. Simple interest adds a fixed amount each period; compound interest reinvests gains so growth accelerates over time. Understanding the difference clarifies savings goals, investment expectations, and borrowing costs. This Interest calculator compares simple and compound outcomes so you can see the impact of rate, time, and compounding frequency on final totals.

It is a practical way to build intuition: small changes in rate or years can produce large differences when compounding is involved. The tool highlights why starting early matters and why high‑APR debt becomes expensive quickly.

Why This Tool Is Useful

Numbers educate. Comparing side by side reveals relationships that are hard to feel intuitively—linear versus exponential growth and the effect of compounding periods. For savers, it motivates consistent contributions; for borrowers, it demonstrates the cost of carrying balances. For students, it reinforces core finance concepts with immediate, visual feedback.

Because processing happens in your browser, experimentation is fast and private. You can adjust rate, years, and compounding frequency to test realistic scenarios.

Key Features

Shows simple interest totals alongside compound totals for the same inputs. Supports common compounding frequencies (monthly, annual, daily) and presents results clearly for easy comparison. Minimal controls keep attention on interpretation rather than configuration.

How to Use

1. Enter the starting amount, annual rate, and number of years.
2. Select a compounding frequency.
3. Click Calculate to view simple and compound totals.
4. Adjust inputs to explore sensitivity and use the insight to guide saving or borrowing decisions.