Compound Interest Calculator

Project the future value of savings or an investment using compound interest, with an optional recurring monthly contribution. Choose your compounding frequency and see the total growth over time.

Initial Amount ($)

Annual Interest Rate (%)

Years

Monthly Contribution ($) — optional

Compounding Frequency

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Why use Compound Interest Calculator?

This calculator projects how a starting balance grows over time under compound interest, with an optional recurring monthly contribution added at your chosen compounding frequency. It is a mathematical projection based on a constant rate, useful for comparing scenarios — not a guarantee of real investment performance, which fluctuates.

Key benefits

Supports recurring monthly contributions on top of a starting balance
Five compounding frequency options
Shows total contributed vs. total interest earned separately

Features

Compound interest projection with configurable frequency
Optional recurring monthly contribution
Breakdown of contributions vs. interest earned

Popular use cases

Projecting retirement or long-term savings growth
Comparing outcomes at different interest rates or time horizons
Estimating how monthly contributions accelerate growth

How to use Compound Interest Calculator

1
Enter your starting amount
Enter the initial amount you are investing or saving.
2
Enter the rate and time
Enter the annual interest rate and the number of years to project.
3
Add a monthly contribution (optional)
If you plan to add money regularly, enter the monthly contribution amount.
4
Choose compounding frequency
Select how often interest compounds — annually, quarterly, monthly, or daily.

Frequently asked questions

What is compound interest?

Interest calculated on both the initial principal and the accumulated interest from previous periods, so growth accelerates over time compared to simple interest.

Does compounding frequency make a big difference?

More frequent compounding (daily vs. annually) produces a slightly higher return at the same stated annual rate, though the difference is usually modest.

Is this projection guaranteed?

No. This is a mathematical projection based on a constant rate you provide — real investments fluctuate and are not guaranteed to match this projection.

Last reviewed: July 2026

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