Investing

Investment Growth Calculator

Project contributions, investment gains, and ending value over time.

● 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

Estimate portfolio growth with monthly contributions and an annual fee deduction. 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—initial portfolio of $25,000, monthly contribution of $500, expected annual return of 7%, annual fee of 0.5%, investment period of 25 years—the calculator returns projected portfolio value of $500,823.21; total contributions: $175,000.00; estimated investment growth: $325,823.21. Change the assumptions to match your own case rather than relying on the example.

Formula and calculation basis

Ending value is calculated by applying the periodic return and then adding each contribution.

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 net assumed return is the entered return minus the annual fee. Test several rates because long-term projections are highly sensitive to assumptions.

Common mistakes to avoid

  • Using historical returns as guaranteed future returns.
  • Ignoring taxes, transaction costs, and irregular contributions.
  • Underestimating the long-term effect of fees.

Limits and assumptions

The model applies a constant monthly net rate and end-of-month contributions. Real returns vary.

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

Frequently asked questions

How are fees modeled?

The annual fee percentage is subtracted from the annual return before monthly compounding.

Are contributions made at the start or end of the month?

They are added after modeled monthly growth.

Can the return be negative?

Yes, provided the inputs remain mathematically valid.

Sources and reference context

Independent educational referencesInvestor.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.