Stock Portfolio Growth & Risk Calculator

How this stock growth calculator works

This free stock investment calculator projects how a portfolio of real US and Canadian stocks could grow. Pick your stocks and, for each one, set two things: what share of your money goes into it (the split) and how fast you expect it to grow each year (its own growth rate). Because every holding is projected at its own rate, a high-growth pick and a steady dividend payer behave differently — just like a real portfolio. You then add a starting amount, optional regular contributions, a portfolio dividend yield, and an inflation rate, and the tool projects the whole mix forward year by year.

Under the hood the calculator treats each stock as its own growing stream. For every period (monthly, quarterly, and so on) it adds your contribution to that stock's balance, then applies its share of the annual return. Returns compound quarterly by default — you can switch to monthly, semi-annual, or annual under the results to see how compounding frequency changes the outcome. At the end it adds up every stream to show your projected balance, splits it into starting amount, contributions, and market growth, and converts the total into today's dollars so inflation doesn't flatter the number.

What each input means

• Split (%) — how your money is divided between stocks. Splits must add up to 100%. The calculator shares them out equally as you add stocks, and you can override any of them.
• Growth rate (%) — your own yearly assumption for how much that stock appreciates in price. This is the number you control; the calculator never predicts it for you.
• Starting amount — a one-off lump sum you begin with. Enter 0 if you're starting from scratch.
• Contribution + frequency — how much you add on a schedule (say $500 a month). Investing a fixed amount regularly is called dollar-cost averaging.
• Dividend % / yr — the portfolio's average dividend yield. Choose whether dividends are reinvested (they buy more shares and compound) or paid out as cash.
• Inflation % / yr — used only to show the "today's dollars" figure, so you can see what your future balance is really worth.
• Compounding — how often growth is applied. More frequent compounding produces a slightly higher result for the same annual rate.

Worked example

Suppose you start with $10,000, add $500 a month for 20 years, and split your money 60/40 between two stocks — one you expect to grow 12% a year and one you expect to grow 7% a year — with a 1.5% dividend yield reinvested and compounding quarterly.

• You will have personally put in $10,000 + ($500 × 12 × 20) = $130,000 over the two decades.
• The 60% stream (12% plus reinvested dividends) grows fastest and does most of the heavy lifting.
• The 40% stream (7%) grows more slowly but steadies the ride.
• The projected balance lands well above your $130,000 of contributions — and that gap is your market growth, the money your money earned.

Change any single input — a higher monthly contribution, one more year, a slightly lower growth assumption — and watch how much the final figure moves. That sensitivity is the real lesson: how much you contribute and how long you stay invested usually matter more than picking the "perfect" stock.

Choosing a realistic growth rate

The growth rate is the most important number you enter, so it's worth grounding it in history rather than hope. Over multi-decade periods the broad US stock market (the S&P 500) has historically averaged roughly 10% a year before inflation, or about 6–7% after inflation — but with large swings, losing years, and no guarantee it repeats. Individual stocks can do far better or far worse than the market and are much less predictable.

Type of holding	Rough historical range*
Broad market index (e.g. S&P 500)	~7–10% / yr
Large, established "blue-chip" stock	~5–10% / yr
Fast-growing individual stock	Highly variable
Dividend-focused stock	~4–8% / yr + dividends

*Long-run averages before inflation, shown only to help you pick a sensible assumption. Past performance does not predict future returns.

A good habit is to run the calculator two or three times — an optimistic rate, a middle rate, and a conservative one — so you see a range of outcomes rather than a single false-precision number.

Key terms

• Compound growth — earning returns on your past returns, not just your original money. It's why the later years of a long projection grow so steeply. (See what compound interest is, or run the numbers in our compound interest calculator.)
• Dividend yield — the annual dividend a stock pays as a percentage of its price.
• Reinvesting dividends (DRIP) — using dividend cash to buy more shares, which then earn their own returns.
• Nominal vs. real — "nominal" is the raw future dollar figure; "real" (today's dollars) strips out inflation so you can compare it to prices now.
• Dollar-cost averaging — investing a fixed amount on a schedule, which buys more shares when prices are low and fewer when high.
• Diversification — spreading money across holdings that don't all move together, which can smooth your overall return.

Common mistakes to avoid

• Using a growth rate that's too high. Assuming 20%+ a year for decades produces exciting but unrealistic numbers. Anchor to history.
• Ignoring inflation. A million dollars in 30 years is worth far less than a million today — always check the "today's dollars" figure.
• Forgetting that returns aren't smooth. Real markets fall as well as rise; a steady projected line hides some very bumpy years.
• Treating the output as a promise. This is a planning tool, not a prediction. Use it to compare choices, not to guarantee a result.

Frequently asked questions

Does this calculator predict stock prices?

No. It never guesses what a stock will do. It grows your money at the rate you enter, so the projection reflects your own assumptions — not a forecast from us.

What growth rate should I use?

A sensible starting point is the long-run market average of around 7–10% a year before inflation, adjusted up or down for how aggressive or conservative each holding is. Running a few different rates gives you a realistic range.

Should I reinvest dividends?

Reinvesting (DRIP) uses dividend cash to buy more shares, which then earn returns of their own — a meaningful compounding boost over long periods. Toggle it off to see dividends paid out as cash instead.

What's the difference between nominal and "today's dollars"?

Nominal is the raw future balance. "Today's dollars" divides that by inflation over the same period, showing what the money would actually buy at today's prices. It's usually the more meaningful figure for planning.

Why give each stock its own growth rate?

Because real portfolios aren't uniform. A high-growth stock and a steady dividend payer are expected to behave very differently, and projecting each at its own rate is far more realistic than applying one blended number to everything.

How does compounding frequency change the result?

For the same annual rate, compounding more often (monthly vs. annually) produces a slightly higher final value, because returns start earning returns sooner. The default here is quarterly; you can change it under the results.

What is volatility, and how does the risk rating work?

Volatility measures how bumpy a stock's ride has been — how far it swings up and down. We turn each stock's real historical volatility into a simple 1–7 risk rating so you can compare holdings at a glance: 1 is calm, 7 is very jumpy.

What does "dollar-cost averaging" mean?

Investing a fixed amount on a schedule (say $200 a month). You automatically buy more shares when prices are low and fewer when they're high, so you don't have to time the market. Choose "Recurring" above to model it.

Why is my mix less risky than the riskiest stock in it?

Because stocks that don't move together partly cancel each other out. Mixing them lowers your overall volatility below the simple average of the parts — that gap is the "diversification benefit," and the tool shows it for your exact mix.

Is this financial advice?

No. It's an educational projection tool. It doesn't recommend any stock or strategy and can't account for your personal situation, taxes, or fees. For decisions about your money, speak to a licensed financial professional.

Are the stock prices live?

Stock prices shown in the picker are updated once daily after the US market close, so they reflect recent closing values rather than live intraday trading.

Estimate only

This is a projection based on the growth rates you enter — real stock returns vary, include losing years, and are never guaranteed. Figures are for illustration only and are not investment, tax, or financial advice. See our disclaimer.