How to Calculate VOO Returns

The VOO return formula

At its core, estimating investment growth uses the compound growth formula:

FV = P × (1 + r/n)^(n × t)

where P is your starting amount, r is the assumed annual return, n is how many times per year the return compounds, and t is the number of years. Our calculator uses monthly compounding, so n = 12.

Compound growth

Compound growth means that gains from earlier periods are assumed to stay invested and generate their own gains in later periods. Over long time horizons, this can make a large difference in the projected outcome compared to simple, non-compounding growth — which is one reason time horizon matters so much in these calculations.

Contributions

When you add a regular monthly contribution, each contribution is projected forward from the month it's made to the end of your time horizon, using the same compounding assumption. The formula for the future value of a series of equal contributions is:

FV = PMT × [((1 + r/n)^(n × t) − 1) / (r/n)]

where PMT is the contribution amount per period. Your total projected future value is the sum of the future value of your initial investment and the future value of your contributions.

Dividend reinvestment

VOO distributes dividends from the underlying companies in the S&P 500. If those dividends are reinvested, they can meaningfully affect total return over long periods, separately from price appreciation. The core VOO calculator above doesn't model dividends separately — your assumed annual return is a single all-in growth figure, and it's up to you whether that represents price growth alone or price growth plus reinvested dividends. If you want dividend income modeled on its own, with your own yield and growth-rate assumptions and an explicit choice to reinvest or take dividends as cash, use the VOO dividend calculator instead.

A full worked example

Say you start with a $10,000 initial investment, add $500 every month for 20 years, and assume a 7% annual return, compounded monthly (n = 12, t = 20, r = 0.07). Here's each formula step computed exactly, not rounded until the final numbers:

Step 1 — future value of the initial investment:
FV = 10,000 × (1 + 0.07/12)^(12 × 20) = 10,000 × (1.005833)^240 ≈ $40,387

Step 2 — future value of the monthly contributions:
FV = 500 × [((1 + 0.07/12)^(12 × 20) − 1) / (0.07/12)] ≈ $260,463

Step 3 — add them together:
$40,387 + $260,463 = $300,851 total projected future value, from $130,000 in total contributions ($10,000 initial + $500 × 240 months) — meaning roughly $170,851 of the total comes from estimated investment growth, not money you put in directly.

You can reproduce this exact scenario, or change any assumption, in the VOO calculator.

Projected vs. historical returns

It's important to distinguish between a projection and a historical return. A projection, like the one this calculator produces, applies an assumption you choose to future years that haven't happened yet. A historical return describes what actually happened over a specific past period, and it will not exactly repeat in the future. Neither this calculator nor any other tool can tell you what VOO will actually return going forward.