FinanceUpdated May 2026

Compound Interest Calculator

Project the future value of your savings or investments with compound interest, regular contributions, and any rate.

100% Free
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Works Offline
Updated 2026

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Use this free compound interest calculator to project the future value of savings or investments with regular contributions.
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Enter your investment details

Start Calculating Your Growth

Enter your investment parameters on the left to see how compound interest can help your money grow

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How Compound Interest Works

1

Principal Growth

Your initial investment earns interest, which is added to your principal.

2

Compounding Effect

Interest starts earning interest, creating exponential growth over time.

3

Regular Contributions

Monthly investments significantly accelerate your wealth building.

Key factors that affect compound growth:

  • Interest Rate: Higher rates dramatically increase your final amount over long periods
  • Time: The longer you invest, the more powerful compounding becomes
  • Contribution Frequency: More frequent compounding (daily vs monthly) yields slightly better returns
  • Regular Investments: Consistent monthly contributions can outperform lump-sum investments

Verified accuracy

Cross-checked against authoritative formulas (IRS, NIST, ACM) and updated for 2025/2026 tax years and rates.

Instant results

No server roundtrip. All math runs in your browser so results appear the moment you finish typing.

Your data stays private

We never collect, store, or transmit your inputs. Every calculation runs locally in your browser.

Learn as you calculate

Each calculator includes the formula, plain-English explanation, and FAQs so you understand the result.

Estimates only. Calculator results are for educational and planning purposes — not professional advice. For binding decisions on taxes, investments, health, or legal matters, consult a qualified professional.

FAQ

Frequently asked questions

Everything you need to know about this calculator. Can't find what you're looking for? Email our team.

It depends on the rate and time. $10,000 at 7% for 30 years with monthly compounding grows to $81,169. At 10% for 40 years, it grows to $452,593. Our compound interest calculator lets you enter any principal, rate, and time to see the exact future value. The compound interest calculator results show how much is from contributions vs interest earned.

How it works

How to calculate compound interest growth

Our compound interest calculator lets you project the future value of an investment with regular contributions and compound growth in five steps.

  1. 1

    Enter the starting balance

    Type the amount you have already saved or invested. Use 0 if you are starting from scratch.

  2. 2

    Enter the annual interest rate

    Type the expected annual return as a percentage. A diversified stock portfolio has historically returned about 7% after inflation.

  3. 3

    Enter the time horizon in years

    Type how many years you plan to let the money grow. Compound interest is most powerful over long horizons.

  4. 4

    Enter your monthly contribution

    Type how much you add each month. Even small regular contributions compound dramatically over decades.

  5. 5

    View the future value

    The calculator shows the final balance, total contributions, interest earned, and a year-by-year growth table.

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