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What is dollar-cost averaging?
Dollar-cost averaging (DCA) means investing a fixed amount at regular intervals — usually monthly — no matter what the market is doing. When prices are low your fixed amount buys more shares; when they are high it buys fewer. Over time this averages your cost per share and removes the pressure of trying to pick the perfect moment to invest. Most people already DCA without naming it: every paycheck contribution into an index fund is dollar-cost averaging.
DCA vs lump sum: which wins?
Studies from Vanguard and others repeatedly find that lump-sum investing beats DCA roughly two-thirds of the time. The reason is simple: markets trend upward, so money invested earlier has more time to compound. DCA's edge is not higher average returns — it is lower regret. By spreading purchases out, you avoid the worst-case timing of putting everything in right before a downturn, and you keep investing through the scary parts. Switch this calculator to Real stock data and try a period that includes a crash (for example a five-year window spanning 2020) to see DCA's protective effect in action.
When DCA makes the most sense
DCA fits naturally when you are investing out of regular income, when you have just received a lump sum but would lose sleep deploying it all at once, or when you are a newer investor building the habit. It works best with broadly diversified ETFs that track markets which have historically risen over time. It offers far less protection on a single falling stock — averaging down into a company in structural decline simply buys more of a loser.
Frequently asked questions
Is DCA better than lump sum?
Statistically lump sum wins about two-thirds of the time because markets usually rise. But DCA wins in downturns and is easier to stick with. If a lump sum would keep you up at night, spreading it over 6–12 months is a reasonable middle ground.
How often should I invest?
Monthly is most common and matches most pay cycles. Weekly averages slightly more smoothly, but the difference is small — consistency matters far more than frequency.
Does this use real prices?
In Real stock data mode it pulls actual adjusted closing prices (which include dividends and splits) and simulates a purchase at every interval across your chosen period. Fixed return mode instead assumes a constant annual rate for a quick comparison with no market data.
What does “average cost per share” mean?
It is your total invested divided by the total shares you accumulated. With DCA it sits somewhere between the cheapest and priciest points you bought at — the whole idea of averaging. Lump sum, by contrast, locks in a single purchase price on day one.