Investing

Compound Interest Calculator

Calculate future value with compounding and optional recurring contributions.

● Runs locally in your browserReviewed June 21, 2026

Enter your assumptions

Currency changes the display symbol only; formulas are currency-neutral.
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What this calculator helps you do

Project the future value of an initial amount plus recurring monthly contributions under a selected compounding frequency. The calculation runs entirely in your browser; SENNA Finance does not receive the values entered into this tool.

Worked example

Example assumptions

Using the default example—starting amount of $10,000, annual return of 7%, years of 20 years, compounds per year of Monthly, monthly contribution of $300—the calculator returns projected future value of $196,665.39; total contributions: $82,000.00; estimated growth: $114,665.39. Change the assumptions to match your own case rather than relying on the example.

Formula and calculation basis

FV = P(1+r/m)^(mt) plus the future value of recurring contributions.

Inputs are converted to the periodic units required by the formula. Results are calculated with full JavaScript numeric precision and rounded only for display.

How to interpret the result

The difference between final value and total contributions is modeled growth, not a guaranteed return. Small changes in rate or time can materially affect long projections.

Common mistakes to avoid

  • Using a nominal return without accounting for fees, tax, or inflation.
  • Treating a steady annual rate as guaranteed.
  • Confusing contribution frequency with compounding frequency.

Limits and assumptions

Returns are constant in this mathematical model. Market volatility, fees, tax, and contribution timing can produce different outcomes.

Outputs are estimates, not contractual quotations, regulated disclosures, tax advice, investment advice, or a substitute for professional review.

Frequently asked questions

What is compounding?

It is growth earned on both the original amount and previously accumulated growth.

Are monthly contributions compounded the same way?

This tool models recurring contributions using a monthly periodic rate.

Does the result account for inflation?

No. Use the inflation-adjusted return calculator for purchasing-power analysis.

Sources and reference context

Independent educational referencesInvestor.gov Compound Interest Calculator ↗Investor.gov — financial tools and investing education ↗SENNA Finance calculation methodology

External references provide educational context and do not imply endorsement of SENNA Finance.

Review record

Prepared and technically reviewed by Subash Gupta

Formula engine v1.1.0. Last reviewed June 21, 2026. The reviewer is a financial-systems and technology practitioner, not a licensed financial adviser. Report suspected errors through the correction channel.