Investment Calculator - Project Your Portfolio Growth

Last updated: July 2026

Visualize Your Portfolio's Growth

Investing in the stock market, mutual funds, or a 401k/IRA is one of the more reliable ways to build long-term wealth, though returns are never guaranteed. This calculator projects how your money could grow over time, separating your own contributions from the growth on top of them. It's a projection based on the assumptions you enter, not financial advice — a financial advisor can help you build an actual plan.

How the Projection Works

The calculator grows your starting balance and your ongoing monthly contributions separately, using your entered annual return rate compounded monthly for both, then adds the two together for your projected future value.

A Worked Example

Using the calculator's own defaults — a $5,000 starting balance, $200 monthly contribution, 8% estimated annual return, over 10 years:

Total contributed out of pocket: $5,000 + ($200 × 12 × 10) = $29,000
Projected future value: approximately $47,700
Growth from compounding: approximately $18,700

These figures are approximate — verify the exact output against the live calculator above, since manual estimates can differ slightly from the tool's precise calculation.

Frequently Asked Questions

It takes your starting balance and adds your regular monthly contributions, then applies your estimated annual return rate over your chosen number of years, compounding monthly. The result separates what you actually put in from what growth (interest) added on top.

For a diversified US stock portfolio, the long-run historical average is roughly 7-10% per year before inflation. For a more conservative mix including bonds, 3-5% is more typical. There's no guaranteed rate — actual returns vary year to year and this isn't financial advice, just a way to model different assumptions.

That's compound growth at work. Over long periods (10+ years), the returns you earn start generating their own returns, so growth accelerates the longer your money stays invested — which is why starting early matters more than the exact return rate in many cases.

They share the same underlying math, but are framed for different use cases. This tool is built around ongoing portfolio contributions — a fixed starting balance plus regular monthly investing, compounded monthly, which matches how most people actually invest (like a 401k or brokerage account). The Compound Interest Calculator exposes more control over compounding frequency (annually, quarterly, monthly, daily) for a more general-purpose interest calculation.

Both use the same formula, but default to different assumptions. This tool defaults to an 8% return, reflecting stock market-style investing. The Savings Calculator defaults to a lower rate (4.5%), reflecting a savings account or CD rather than market investing. Use whichever default fits what you're actually planning for, and adjust the rate either way.

No — this is a gross growth projection based on the return rate you enter. Real accounts may be affected by taxes (depending on account type, like a taxable brokerage vs. a 401k or Roth IRA), fund expense ratios, and other fees, all of which would reduce your actual net return.

Both help, but they behave differently. A lump sum invested today has the longest possible time to compound. Monthly contributions add smaller amounts throughout the period, so each contribution has less time to grow than the initial balance does. This calculator models both happening together, which reflects how most people actually invest.