Lump Sum vs Dollar-Cost Averaging Calculator
Compare investing a lump sum all at once against spreading the same total over several months (DCA) at an assumed return. Educational, not investment advice. Runs in your browser.
DCA invests total ÷ months each month.
At a constant positive return, investing a lump sum up front beats spreading it out, because more money is in the market earning for longer — which is why lump-sum wins in this steady-return model and historically wins most of the time. DCA’s real advantage is risk management: it reduces the chance of investing everything just before a drop, and it matches how people save from income. This model assumes one steady return and ignores volatility, the very thing DCA hedges. Educational, not investment advice. Everything runs in your browser.
About this tool
When you have a sum of money to invest — an inheritance, a bonus, proceeds from a sale — you face a classic choice: put it all in at once (lump sum) or spread it out in equal installments over time (dollar-cost averaging, DCA). This calculator compares the two for the same total amount at an assumed steady return. The lump sum is invested entirely at the start and compounds for the full period, so its future value is total × (1 + monthly return)^months. The DCA approach invests an equal slice each month, modeled as an ordinary annuity, so a portion of the money sits in cash waiting its turn and therefore spends less time compounding. The mathematical consequence is unambiguous in this steady-return model: whenever the assumed return is positive, lump sum wins, because more capital is working in the market for longer. That also matches the historical evidence — studies (notably by Vanguard) have found that investing a lump sum immediately outperformed DCA roughly two-thirds of the time across markets and periods, simply because markets rise more often than they fall. So why does anyone DCA? Two good reasons this model deliberately does not capture. First, risk: spreading purchases reduces the damage of investing everything right before a downturn, lowering the dispersion of outcomes and the regret of bad timing — valuable if a near-term drop would shake you out of the market. Second, practicality: most people invest from ongoing income, so they are DCA-ing by necessity, not choice. The honest framing is that lump sum has the higher expected value while DCA offers psychological and timing-risk benefits. Because this tool assumes a single constant return, it inherently favors lump sum and cannot show the volatility scenarios where DCA shines. It is educational and explicitly not investment advice. Everything runs in your browser; nothing is uploaded.
How to use it
- Enter the total amount you have to invest.
- Enter the number of months over which DCA would spread the investment.
- Enter an assumed annual return.
- Compare the projected final values and see which approach comes out ahead under a steady return.
Frequently asked questions
- Does lump sum or DCA produce more money?
- At a constant positive return, lump sum always wins because the full amount compounds for longer. Historically, investing a lump sum immediately has outperformed DCA roughly two-thirds of the time, since markets rise more often than they fall.
- Then why would I dollar-cost average?
- DCA reduces timing risk — the chance of investing everything just before a drop — and lowers the range of outcomes. It is also how most people invest from regular income. The benefit is risk management and psychology, not higher expected return.
- How is each future value calculated?
- Lump sum: total × (1 + monthly return)^months. DCA: equal monthly investment as an ordinary annuity, total ÷ months × ((1 + i)^n − 1) ÷ i. The DCA money invested later compounds for less time.
- Why does this tool always favor lump sum?
- Because it assumes one steady return with no volatility. DCA's advantage shows up specifically in volatile or falling markets, which a constant-return model cannot represent. Treat the comparison as the expected-value case, not a guarantee.
- What does the research say?
- Vanguard and others have found lump-sum investing beat DCA about two-thirds of the time historically. But DCA reduced the worst-case outcomes, which is why risk-averse investors or those worried about near-term drops may still prefer it.
- Is this investment advice?
- No. It is an educational comparison under simplifying assumptions. Markets are volatile and returns are not guaranteed. Nothing is uploaded; all math runs in your browser.