Regular investing

Dollar-Cost Averaging Calculator (DCA)

Backtest dollar-cost averaging into a real stock or ETF with actual daily prices and dividends since October 1, 2020, and compare it with investing the same total as a lump sum, or project recurring investments at a return you choose.

Free calculator

Model regular investing

Schedule

Optional. Invested on the first day.

Period

From Oct 1, 2020 onward. Runs through the latest close; a closed-market date buys on the next trading day.

Backtest
Run a backtest
Enter a ticker and start date, then run it to see what regular buying would be worth today, using actual daily closes and dividends, next to the same total invested all at once.

How the historical backtest works

Choose “Backtest a real stock or ETF”, enter a ticker, an amount, how often you invest and a start date from October 1, 2020 onward. Each scheduled purchase buys at that day's closing price, or the next trading day's when markets were closed, and the schedule runs through the latest close. Closes are adjusted for splits but not for dividends, so each dividend is counted once: reinvested at the close on its ex-dividend date, or kept as cash. A stock or fund that began trading after your start date begins buying on its first trading day.

The lump-sum comparison takes the entire amount the schedule eventually invests and puts all of it in on the first purchase date, with dividends handled the same way. Both use the same total money and the same dates. It assumes you had the whole sum on day one; if your cash arrives with each paycheck, investing it as it becomes available is a different choice from the one this comparison measures.

Example: $500 a month into SPY, starting Monday, January 4, 2021, with dividends reinvested. Purchases fall on the 4th of each month, or the next trading day, through the latest close, so the result updates each trading day and shows the exact dates and number of purchases used. Open this scenario.

How to use the DCA Calculator

  1. Choose an amount and how often you invest it. Add a starting amount if you begin with a lump sum.
  2. To project forward, set the number of years and an annual return assumption.
  3. To see what really happened, switch to the backtest, enter a ticker and a start date, and run it.

How the calculation works

In the backtest, each scheduled contribution buys shares at the close on its date, or the next trading day when markets were closed, so the number of shares bought rises when the price falls. Closes are split-adjusted but not dividend-adjusted, so each dividend is counted once: reinvested at its ex-dividend date close or kept as cash. The lump-sum comparison invests the entire total the schedule eventually contributes on the first purchase date. In the projection, each contribution is invested at the start of its period and compounds at the per-period equivalent of your annual return.

Formula

Shares bought = amount / closing price that day

Average cost = total invested / shares bought

Value = shares held x latest close

Worked example

Investing $500 a month for 20 years puts in $120,000. At a steady 7% a year, the balance reaches about $86,000 after 10 years and $255,200 after 20.

That makes $135,200 of the ending value growth and 47% money contributed. Most of the growth arrives in the later years, once the balance is large.

What the results mean

  • An average cost below today's price means the position is ahead; DCA lowers average cost most in volatile stretches.
  • The lump-sum figure is the entire amount the schedule eventually invests, all put in on the first purchase date. It assumes the whole sum was on hand that day, which is a different choice from investing cash as it becomes available.
  • The annualized figure is a money-weighted return: each purchase counts from its own date. It is not the same as a fund's published time-weighted return, which ignores when money was added.

Assumptions and limitations

  • Backtests use daily closes adjusted for splits, from October 1, 2020 onward, through the latest close.
  • A stock or fund that began trading after the start date starts buying on its first trading day.
  • Fractional shares are bought; taxes, commissions and fund expenses beyond the price are not deducted.
  • Projections use one steady return; real returns vary every year.
  • Past results for a stock or period do not predict future ones.

DCA Calculator FAQ

What is dollar-cost averaging?

Dollar-cost averaging (DCA) means investing the same amount on a regular schedule, such as $500 every month, whatever the price. A fixed amount buys more shares when the price is low and fewer when it is high, so your average cost per share ends up below the average of the prices you paid on.

How does the backtest work?

Each scheduled purchase buys at that day's closing price, or the next trading day's, from your start date to the latest close. Prices and dividends are adjusted for stock splits. Dividends can be reinvested at the close on their ex-dividend date or kept as cash.

Is dollar-cost averaging better than investing a lump sum?

In a market that mostly rises, investing everything at once has usually ended ahead, because more money is invested for longer. DCA tends to win when prices fall after the start. The backtest compares the same total money over the same dates: the lump sum is the full amount the schedule eventually invests, put in on the first purchase date. That only applies if you had the whole sum on day one; if cash arrives with each paycheck, investing it as it comes is the realistic alternative.

What does the annualized return mean for regular investing?

It is a money-weighted return: the yearly rate at which every purchase, each compounding from its own date, would grow to the ending value. A simple return on the total invested understates performance, because the later purchases had little time to grow. A fund's published return is time-weighted instead, measuring the fund regardless of when money went in, so the two can differ for the same fund and dates.

Does the projection predict future returns?

No. The projection applies the steady yearly return you choose. Real returns vary from year to year, so treat the result as a scenario, and use the backtest to see how regular investing actually played out.