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Investing & Savings

Investment Calculator

Project an investment balance and separate contributions from estimated growth.

Best for: Project an investment portfolio balance and distinguish contributed capital from estimated market growth.

Your assumptions

Calculate your estimate

Your result

Investment estimate

Projected balance
$300,850.72
Total contributions
$130,000.00
Estimated growth
$170,850.72

Where the projected balance comes from

Investment Calculator: formula, examples, and planning guide

An investment projection connects four controllable assumptions: what you have, what you add, how long you invest, and the return you use for planning.

What this investment growth estimate includes

The calculator projects a starting portfolio and equal end-of-month contributions with monthly compounding. It separates total money contributed from estimated market growth so you can see which part of the outcome comes from saving versus returns.

It does not simulate market volatility, taxes, withdrawals, fund expenses, or contribution timing within each month. Use a lower return to roughly account for fees or a more conservative portfolio.

A practical three-scenario investment plan

For a $25,000 starting portfolio with $750 added each month for 20 years, compare several annual return assumptions rather than relying on one forecast.

Illustrative 20-year investment scenarios with $25,000 initially and $750 monthly
ScenarioAnnual returnPlanning use
Conservative4%Tests whether contributions can carry more of the goal
Base case7%A middle planning assumption, not a guarantee
Optimistic10%Shows upside while preserving the same contribution plan

The assumptions worth stress-testing first

Contribution level and time are usually easier to control than return. If the target is far away, test whether a modest monthly contribution increase has more dependable impact than assuming better performance.

  • Test fees by subtracting them from the expected annual return.
  • Use a shorter horizon for money with a fixed near-term deadline.
  • Model withdrawals as lower contributions or split the plan into separate phases.

How to use this investment calculator

Use this investment calculator to create a simple accumulation range for a portfolio. The result separates money invested from modeled growth, helping you test whether a goal depends more on savings behavior, time, or an aggressive return assumption.

  1. 1

    Enter investable capital

    Use the current amount allocated to the goal, excluding cash needed for near-term expenses.

  2. 2

    Set contributions and expected return

    Choose a recurring contribution and a diversified after-fee return assumption.

  3. 3

    Run conservative and optimistic cases

    Compare multiple rates rather than relying on a single long-term forecast.

Worked planning example

Example: fund a 20-year investment goal

Set up

Enter the current portfolio and planned monthly investment over a 20-year horizon.

Compare

Compare 5%, 7%, and 9% return cases while keeping contributions unchanged.

Takeaway

If the goal works only at the highest return, increasing contributions may be more controllable than assuming better markets.

Use return ranges instead of promises

Long-term market outcomes are uneven, and sequence, fees, taxes, and behavior can materially change realized results.

  • Use returns net of expected fees.
  • Match risk to the goal’s time horizon.
  • Review allocation and contribution changes regularly.

Calculation methodology and assumptions

For this investment estimate, Silvia uses starting amount, monthly contribution, estimated annual return, time horizon. Project an investment balance and separate contributions from estimated growth. Results are estimates, not quotes, tax advice, or investment recommendations.

Frequently asked questions

What return should I enter?

Use a range consistent with the portfolio’s asset mix, fees, and horizon rather than a recent one-year result.

Does this model market volatility?

No. It applies a steady rate, so it does not show drawdowns or sequence-of-returns risk.

Does the estimate include taxes?

No. Taxable distributions, gains, and account type can change after-tax outcomes.

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