Lump sum vs dollar-cost averaging: how to invest a windfall
You’ve got $50k to invest. All at once, or spread over a year? The data leans one way, but the right answer depends on your stomach as much as the math.
| Lump sum | DCA | |
|---|---|---|
| Average outcome | Higher (markets usually rise) | Slightly lower |
| Risk of bad timing | Higher | Lower |
| Cash drag | None | Yes — uninvested cash waits |
| Regret if it drops | High | Lower |
| Best for | Long horizon, steady nerves | Nervous investors, big sums |
Why lump sum usually wins
Markets rise more often than they fall, so money invested sooner spends more time compounding. Studies (famously Vanguard’s) find lump-sum beats DCA roughly two-thirds of the time. Project either path in the DCA calculator.
When DCA is the smarter choice
If a 20% drop right after investing would make you panic-sell, DCA’s smoother ride is worth the small expected cost — the best strategy is the one you’ll stick with. And for money you earn over time, DCA isn’t a choice, it’s just investing. See the DCA guide.
The verdict
Investing a windfall? Lump sum wins on average thanks to more time in the market. Choose DCA if the risk of bad timing would rattle you into selling. For ongoing contributions from income, you’re dollar-cost averaging by default.
Frequently asked questions
- Does lump sum really beat DCA?
- On average, and about two-thirds of the time historically, because markets trend up. DCA trades a little expected return for less timing risk.
- How long should I spread DCA over?
- If you choose DCA for a lump sum, 6–12 months is common. Spreading longer leaves more cash uninvested (cash drag).
- Isn’t investing from my paycheck just DCA?
- Yes — contributing each payday is dollar-cost averaging by nature. The lump-sum debate only applies to money you already have on hand.
Settle it with your numbers
Free, in-browser calculators for everything above.