Dividend reinvestment (DRIP) calculator

How the formula works

A dividend-paying stock hands you two returns: the price rises, and it pays a dividend along the way. What you do with that dividend is the whole question here. This calculator works one year at a time. The portfolio starts at value \(P\). Each year it earns a dividend equal to its current value times the current yield \(y_t\), and its price appreciates at \(a\). The yield itself drifts a little each year — dividends per share grow at \(g\) while the price grows at \(a\), so the yield, being dividends over price, moves by the ratio of the two:

From there the two paths split. Reinvesting puts the dividend straight back in, so the value compounds at appreciation plus yield — nothing leaves the account:

Taking the cash lets the portfolio appreciate on its own while each dividend is set aside as cash that no longer compounds. Your total wealth is the appreciated portfolio plus the pile of collected dividends:

The reinvestment advantage is the gap between the two totals, \(V^{\text{reinvest}} - V^{\text{cash}}\): the very same dividends, compounded instead of pocketed. For a single year the two paths are identical — a dividend reinvested at the end of year one has had no time to grow. The advantage is entirely a story about time: each reinvested dividend earns its own return, and those returns earn returns, so the gap starts at nothing and widens every year. This is why reinvested dividends have historically supplied a large share of the stock market's long-run total return — price appreciation is only half the engine, and the dividend half only pulls its weight if you let it compound.

What each input means

Starting investment — \(P\)

What you put in today. Both paths start here; they only diverge in what happens to the dividends the position throws off.

Dividend yield — \(y_0\)

This year's dividend as a percent of the position's value. A broad US index yields roughly 1.5–2%; dividend-focused funds and many individual payers run 3–5%. It is the starting yield — the model lets it drift as dividends and price grow at different rates.

Annual dividend growth — \(g\)

How fast the dividend per share rises each year. Steady raisers grow payouts in the mid-single digits; this is what turns a modest starting yield into a large yield on cost after a decade or two.

Share price appreciation — \(a\)

How fast the price grows each year, before dividends. When appreciation and dividend growth are equal the yield stays flat; when dividends grow faster, the yield creeps up over time, and vice versa.

Years — \(n\)

How long the money stays invested. Time is the input the reinvestment advantage lives on: over one year there is no advantage at all, and over thirty it can rival the entire cash you would otherwise have collected.

Reinvest or take cash

The lever this tool exists to illustrate. Reinvesting compounds every dividend inside the portfolio; taking cash pulls each dividend out to spend or hold, appreciating the shares alone. The worksheet shows both and names the gap.

A worked example

Take the worksheet's defaults: $20,000 invested at a 3% starting yield, dividends growing 5% a year, the share price appreciating 4% a year, held for 20 years.

In year one the dividend is 3% of $20,000 = $600. Reinvested, the portfolio becomes $20,000 × (1 + 4% + 3%) = $21,400; taken as cash, the shares grow to $20,800 and you hold $600 in cash — the same $21,400 of total wealth either way. The paths are identical after one year. Then they separate.

Because dividends grow 5% while the price grows 4%, the yield drifts up by a factor of (5% over 4%) each year, reaching about 3.6% of value by the final year. Over the full 20 years the reinvesting portfolio compounds to $81,704, having earned $28,180 in dividends along the way, all of it put back to work. Take those dividends as cash instead and you end with $43,822 in shares plus $19,840 of collected cash — $63,662 of total wealth. The difference, $18,042, is the reinvestment advantage: about 28% more wealth for the single decision to let the dividends compound.

Assumptions and limits

• The yield, dividend growth and price appreciation are all constant. Real dividends get cut in bad years, real prices swing, and real yields wander — a smooth projection models none of that. Treat the output as what the assumptions imply, not a forecast.
• There is no volatility and no sequence-of-returns risk. Reinvesting during a downturn actually buys more shares cheaply, which a straight-line model cannot show; the real advantage of reinvesting is often understated here, not overstated.
• Taxes are ignored. In a taxable account, dividends are taxed in the year they are paid — at the lower qualified-dividend rates for most US stocks — even when reinvested, which quietly drags on the compounding this tool shows. Reinvesting inside an IRA or 401(k) avoids that drag entirely, so the untaxed figures here are closest to reality for a tax-sheltered account.
• Reinvestment is assumed frictionless and immediate, in whole-dollar terms rather than whole shares. Most brokers and DRIP plans now support fractional reinvestment for free, so this is a mild idealization.
• This is arithmetic, not advice. It shows what the inputs imply; it cannot know what a stock will yield, grow or return.

Questions people ask

What is a DRIP?

A DRIP is a dividend reinvestment plan: instead of paying a dividend to you as cash, it uses the money to buy more shares of the same position automatically, usually including fractional shares and usually for free. The effect is that every dividend immediately goes back to work earning its own dividends and price gains. Many companies offer a DRIP directly, and virtually every broker offers automatic reinvestment on the funds and stocks you already hold.

How much of stock returns come from dividends?

Historically a large share. Over long stretches of US market history, reinvested dividends and their compounding have accounted for a substantial portion of total return — by many long-run measures roughly a third to a half, though the exact figure depends heavily on the period and index chosen. The point is descriptive, not a promise: price appreciation alone understates what a dividend-paying portfolio has delivered, and the dividend contribution only shows up in full if the dividends were reinvested rather than spent.

Are reinvested dividends taxed?

Yes, in a taxable account. A dividend is taxable income in the year it is paid whether you take it as cash or reinvest it — reinvesting does not defer the tax. For most US stocks these are qualified dividends taxed at the lower long-term capital-gains rates, but tax is still due, and it comes out of pocket since the cash was plowed back into shares. Inside an IRA, 401(k) or other tax-sheltered account there is no annual tax on the dividend, which is why reinvesting compounds fastest there.

Does reinvesting still make sense in retirement?

It depends on whether you need the income. Reinvesting is a growth choice: it forgoes spendable cash today to build a larger position for tomorrow. In retirement many people flip the switch and take dividends as cash to live on, precisely the second mode this calculator models. There is no universally right answer — a retiree with other income may keep reinvesting, while one relying on the portfolio for expenses will take the cash. The tool lets you price the trade-off both ways.

What is the difference between yield and yield on cost?

Yield is this year's dividend divided by the position's current value — what a new buyer would get today. Yield on cost divides the current dividend by what you originally paid. Because dividends tend to grow over time while your cost stays fixed, yield on cost climbs the longer you hold: a stock bought at a 3% yield that doubled its dividend now yields 6% on your original cost, even if new buyers still see 3%. It is a measure of how far a holding has come, not a rate available in the market today.