Compound Interest Calculator

See how compound interest grows your money over time. Enter your principal, interest rate, compounding frequency, and time period to calculate the future value of your investment or savings.

Initial Amount ($)

The starting amount you invest or deposit.

Annual Interest Rate (%)

The annual interest rate or expected return.

Compounding Frequency

How often interest is calculated and added.

Time Period (years)

How long the money grows.

How to Use

1 Enter your initial deposit or investment amount.

2 Enter the annual interest rate.

3 Select how often interest compounds.

4 Enter the number of years.

5 Click Calculate.

Formula

Future Value P × (1 + r/n)^(n × t)

Where P = principal, r = annual rate, n = compounds/year, t = years

Total Interest Future Value − Principal

Growth % (Interest ÷ Principal) × 100

Example Calculation

If you invest $10,000 at 7% annual rate, compounded monthly for 10 years:

FV = $10,000 × (1 + 0.07/12)^(12×10)
FV = $10,000 × (1.005833)^120
Future Value = $20,096.61
Total Interest = $20,096.61 − $10,000 = $10,096.61
Growth = 100.97%

Your money more than doubles in 10 years!

Why It Matters

Compound interest is one of the most powerful forces in finance. It means you earn interest on your interest, creating exponential growth over time. The earlier you start saving or investing, the more time compound interest has to work in your favor. Even small amounts grow significantly over long periods.

Who Uses This Calculator?

• People comparing loan, mortgage, salary, savings, tax, or investment scenarios before making a money decision.
• Homeowners, borrowers, employees, freelancers, and small business owners who need fast estimates without a spreadsheet.
• Anyone who wants to understand the inputs, formula, and tradeoffs behind a financial result.

Frequently Asked Questions

What is compound interest?

Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. Unlike simple interest (which is only calculated on the principal), compound interest causes your money to grow at an accelerating rate over time. This is why it is often called "interest on interest."

How often is interest compounded?

It depends on the account or investment. Savings accounts typically compound daily or monthly. Certificates of deposit (CDs) may compound daily, monthly, or quarterly. Bonds often compound semi-annually. More frequent compounding results in slightly higher returns, though the difference becomes smaller as frequency increases.

What is the difference between simple and compound interest?

Simple interest is calculated only on the original principal amount. Compound interest is calculated on the principal plus all previously earned interest. For example, $10,000 at 7% simple interest earns $700/year ($7,000 over 10 years). At 7% compound interest (monthly), it grows to $20,097 — earning $10,097 in interest over the same period.

How does compounding frequency affect returns?

More frequent compounding generates slightly higher returns because interest is added to the principal more often, so the next compounding period starts with a larger base. The difference between annual and daily compounding on $10,000 at 7% for 10 years is about $150. It matters, but the rate and time matter much more.

Can I add regular contributions?

This calculator currently handles a single initial deposit. For regular monthly contributions (like retirement savings), the total would be even higher. We plan to add a contribution feature in a future update. For now, you can estimate by running separate calculations and adding them together.

Related Guides

Compound Interest Guide

See how time, returns, and recurring contributions affect long-term savings growth.

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This calculator provides estimates for informational purposes only and is not financial, tax, or legal advice. Consult a qualified professional before making financial decisions.