Saving & Investing

Investment Return Calculator

Most real investing involves both a starting balance and ongoing monthly contributions. This calculator projects how both grow together over time at a chosen rate of return.

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Total Contributed
Total Growth

How It Works

The projection adds two future values together: your initial deposit compounding on its own, and a monthly contribution stream compounding as it's added (a standard annuity calculation). Both use your expected monthly return rate, derived from the annual rate you enter. This is a projection based on a constant assumed rate — real markets fluctuate year to year, so treat the output as a planning estimate, not a guarantee.

Worked Example

Starting with $3,000 and contributing $250/month at an 8% expected annual return, 15 years later the projected balance is roughly $96,400. Of that, you'd have personally contributed about $48,000 — the remaining $48,400 or so comes entirely from investment growth, meaning growth roughly equals contributions over that stretch. Extend the same scenario to 25 years instead of 15, and the projected balance jumps to around $260,000, even though total contributions only rise to $78,000 — a clear illustration of why the number of years invested tends to matter more than the size of any single contribution.

Frequently Asked Questions

Why does starting early matter so much?
Because each dollar invested has more time periods to compound. A contribution made in year one compounds for the entire investment horizon, while the same dollar contributed near the end barely grows at all — early contributions carry outsized weight in the final total.
Should I use an average market return or a more conservative number?
Long-run historical averages for diversified portfolios are commonly cited, but future returns are never guaranteed. Many planners suggest testing your projection at a couple of different rates — including a more conservative one — to see how sensitive your goal is to market performance.

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