Compound Interest Calculator

Compound Interest Calculator

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Free Compound Interest Calculator

Calculate how your savings and investments grow over time with our free compound interest calculator. Whether you're planning for retirement, saving for a goal, or comparing investment scenarios, this tool provides detailed projections with interactive charts.

How to Use

  1. Enter your initial investment amount
  2. Set the annual interest rate and compounding frequency
  3. Add regular contributions (monthly, weekly, etc.)
  4. Optionally adjust for inflation and taxes
  5. Click Calculate to see your projected growth

Features

  • Regular contributions — Model monthly, weekly, or annual deposits
  • Inflation adjustment — See your returns in real purchasing power
  • Tax impact — Factor in tax rates on interest income
  • Interactive chart — Visualize growth of principal vs. interest
  • Year-by-year breakdown — Detailed table of balances over time
  • Export results — Download as CSV or JSON
  • Client-side calculations — Inputs and results stay in your browser

The Power of Compound Interest

Compound interest is often described as interest earning interest. Starting early and contributing regularly are two powerful factors because each period's gains can become part of the balance used for future growth.

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 grows exponentially over time — making it one of the most powerful concepts in finance.
How is compound interest calculated?
The formula is A = P(1 + r/n)^(nt), where P is the principal, r is the annual interest rate, n is the number of times interest is compounded per year, and t is the number of years. Our calculator also accounts for regular contributions and inflation adjustments.
What is the difference between APR and APY?
APR (Annual Percentage Rate) is the stated interest rate without accounting for compounding. APY (Annual Percentage Yield) includes the effect of compounding and represents the actual annual return. APY is always equal to or higher than APR.
How often should interest be compounded?
More frequent compounding yields slightly higher returns. Daily compounding earns more than monthly, which earns more than annually. However, the difference between daily and monthly compounding is usually minimal for most savings accounts.
How does inflation affect my savings?
Inflation reduces the purchasing power of your money over time. Our calculator lets you toggle inflation adjustment to see your returns in "real" (inflation-adjusted) terms. A 7% return with 3% inflation gives approximately 4% real growth.
Is my financial data stored?
No. Calculation inputs and results stay in your browser and are not sent to our servers. The site may still use analytics or advertising cookies as described in the privacy policy.
What is the Rule of 72?
The Rule of 72 is a quick way to estimate how long it takes to double your money. Divide 72 by your annual interest rate. For example, at 8% interest, your money doubles in approximately 72 ÷ 8 = 9 years.

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