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Compound Interest Calculator

Project investment growth with compound interest — set the rate, compounding frequency, duration and optional monthly contributions.

Future value

20,096.61

Total contributed
10,000.00
Interest earned
10,096.61

A = P(1 + r/n)^(nt), with monthly contributions compounded at the equivalent monthly rate. For estimation only — not financial advice.

About Compound Interest Calculator

The Compound Interest Calculator projects how an investment grows when interest earns interest. Enter a starting amount, annual rate, duration and compounding frequency — optionally with a monthly contribution — and see the future value, total contributions and interest earned.

Compounding frequency matters: the same 7% rate grows faster compounded monthly than yearly. Regular monthly contributions are compounded month by month, which is how most SIPs and savings plans actually work.

It's a planning tool for savings accounts, fixed deposits, index funds and retirement projections. Results are estimates — real returns vary — and nothing here is financial advice.

How to Use the Compound Interest Calculator

  1. Enter your initial amount and expected annual rate.
  2. Set the number of years and how often interest compounds.
  3. Optionally add a monthly contribution.
  4. Read the projected future value, total contributed and interest earned.

Features

  • Yearly to daily compounding frequencies
  • Optional recurring monthly contributions
  • Shows contributions vs. interest split
  • Instant recalculation as you type

Frequently Asked Questions

What formula does it use?

A = P(1 + r/n)^(nt) for the lump sum, where n is compounds per year and t is years. Monthly contributions are grown with the equivalent monthly rate as an annuity.

How powerful is compounding really?

At 7% compounded monthly, money roughly doubles every 10 years — so $10,000 becomes about $20,100 in 10 years and $40,400 in 20, without any additional deposits.

Is the Compound Interest Calculator free?

Yes, the Compound Interest Calculator is completely free with no usage limits. No signup, no account and no installation required.

Is my data safe?

Yes. All processing happens locally in your browser using JavaScript — nothing you type is uploaded or stored on our servers.

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