Dollar-Cost Averaging vs Lump Sum: What the Math Says

Calculators do the heavy lifting, but knowing what is going on underneath is what saves you money — or stress — later. Vanguard ran the numbers across 90 years of market data. Lump sum beats DCA about two-thirds of the time. DCA still has its place.

The math of DCA

Splitting one big investment into 12 monthly buys reduces price-timing risk but, on average, costs about 2.4 percentage points of return.

Why people still DCA

Behaviour beats math when fear of regret would otherwise keep money in cash forever.

When DCA actually wins

In sideways or falling markets, DCA buys cheaper average shares. That is roughly one year in three.

Pro tips

• If you have a lump sum, invest it within 6–12 months unless the position is huge relative to your net worth.
• Automate DCA on payday so emotion never makes the call.

Frequently asked questions

Is DCA the same as auto-investing? Yes — automatic monthly contributions are DCA in disguise, and they are the right default for most people.

Does DCA work for crypto? Same logic, higher volatility. DCA flattens the bumps but does not protect from a permanent loss.

The math is the easy part. Acting on what it tells you is where the real win lives.