Compound Interest Calculator

Introduction

Compound interest is easiest to understand when contributions and earned interest are shown separately. This calculator helps you explore how a starting balance, monthly deposits, interest rate, time horizon, and compounding frequency may combine over years.

About this compound interest tool

The page is useful for savings accounts, regular investing plans, junior savings, retirement projections, or any goal where money may earn returns on previous returns. It does not promise a return; it simply makes the growth mechanics visible so you can compare scenarios with the same assumptions.

How this tool works

The calculator adds your planned contributions over the selected term and applies the annual rate at the compounding interval you choose. Changing the term or monthly deposit often has a larger effect than small rate changes, so test several combinations before treating one result as a plan.

1. Enter your starting balance and any monthly contribution you plan to add.
2. Add the expected annual interest rate and the number of years.
3. Choose how often interest compounds, then review the projected final balance and interest earned.

When to use this tool

Use it at the start of a savings plan, when reviewing whether a monthly contribution is enough, or when explaining why starting earlier can matter. For products with fees, tax, variable rates, or investment volatility, adjust expectations and verify details with the provider.

Good to know

• This calculator is for planning only and does not include tax, product fees, inflation, or investment risk.
• Small changes to the rate or contribution can have a large effect over long periods, so test several scenarios.