Dollar-Cost Averaging vs Lump Sum: Which Should You Choose?

Capital at risk. Both approaches described here put money into investments that can fall in value, including below what you paid. Neither is a way to avoid loss. This is general information, not personalised advice.

If you already hold a lump sum in cash, investing it all at once has historically left investors better off about two times in three; spreading it out (dollar-cost averaging) has historically done better about one time in three, and it limits how much you lose if prices fall straight after you start. So the default answer is lump sum. Spread it only if a sharp early fall would make you sell — and if you do, fix the schedule in writing before the first instalment.

This page is about deploying money you already have: an inheritance, a bonus, the proceeds of a house sale. If your question is how to set up a monthly contribution from your salary so it does not quietly stop working, that is covered in automatic investing: set-up and failure points.

What the evidence says, exactly

Vanguard's research paper Cost averaging: Invest now or temporarily hold your cash? (Megan Finlay and Josef Zorn, February 2023) is the most cited study on this question. Its findings, read in the paper itself:

The test split a lump sum into three equal parts invested a month apart, assumed a 100% equity portfolio, and assumed the uninvested cash earned nothing. The paper reports similar results for the US, UK, Australia, Canada and the EU, and concludes that most investors — "particularly those without significant aversion to loss" — should invest a lump sum immediately. It also notes that cost averaging "temporarily lowers a portfolio's risk" and may help loss-averse investors stay committed to their plan.

Two things follow. The reason lump sum usually wins is simple: markets have risen more often than cash over most periods, so money waiting to be invested tends to miss out. And "usually" is not "always" — roughly one year in three, the patient investor did better.

A worked example: 60,000 invested two ways

The arithmetic is easiest to see with a made-up price path. Suppose you have 60,000 and a fund priced at 100. You can invest it all today, or invest 10,000 a month for six months. Cash waiting to be invested earns nothing in this example. These prices are hypothetical, not a forecast.

Path 1 — the price falls, then recovers to where it started (100, 80, 85, 90, 95, 100):

Path 2 — the price rises steadily (100, 104, 108, 112, 116, 120):

Each unit count is the amount invested divided by that month's price; the six monthly purchases are added together. Path 1 is the scenario people fear, and averaging wins by 5,902 and caps the early paper loss at 2,000 instead of 12,000. Path 2 is the scenario history has delivered more often, and investing at once wins by 6,291. The study above tells you how often each kind of path has happened; the example shows what each costs you when it does.

Two different things share one name

Much of the disagreement online comes from mixing two situations.

Investing from income — part of each salary goes into a fund every month. There is no lump sum and no choice to make; you are averaging in automatically. Nobody argues against it.

Deploying a lump sum gradually — the whole amount is already yours, in cash, and you choose to drip it in. This has a real cost (time out of the market) and a real benefit (a smaller worst case early on). It is the only version this page weighs up.

Which one fits your situation

The pattern in that table is that the arguments for spreading are about you, not about markets. Your reaction to a fall is a real input. A plan you abandon after the first bad month is worse than either plan followed through.

The case for caution near retirement

The strongest argument against investing everything at once applies to people deploying most of their wealth close to the point of spending it. A retiree is not playing a repeated game; there is no long run in which the averages work out for them personally. A bad year arriving just after the money goes in can permanently reduce what the portfolio can pay out — the same problem explained in sequence-of-returns risk.

That case is strong for a 64-year-old investing a pension lump sum and weak for a 30-year-old investing a modest bonus into a portfolio they will add to for decades. Treating one person's caution as a rule for the other is the common mistake.

How to run a spread schedule properly

A vague plan to "put some in when things settle down" is not averaging; it is market timing, and the moment never announces itself.

Waiting for a better entry point is not a third option. It requires being right twice — when to stay out and when to get back in — and the strongest up days tend to come during the same volatile stretches that make nervous investors hold cash. Both approaches on this page get you invested; indefinite waiting does not.

Bottom line

Lump sum is the evidence-based default. Spreading over a short, written schedule is a reasonable price to pay if you know a sharp early fall would make you sell. After that, the outcome depends far more on staying invested and keeping fund costs low than on which month you started.

Frequently asked questions

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

Not on average. In Vanguard's 1976–2022 analysis of global equities, a lump sum beat three-month cost averaging 68% of the time over one-year periods. Averaging did better the rest of the time, mostly when prices fell soon after the start.

How long should I spread a lump sum over?

Keep it short and fixed: three to twelve months is typical, and Vanguard's test used three. The longer the schedule, the longer part of the money sits in cash, which is the main cost of averaging.

Is dollar-cost averaging better than keeping the money in cash?

Historically yes. Vanguard found cost averaging beat staying entirely in cash 69% of the time over one-year periods, so a gradual plan is still far better than waiting indefinitely.

Does my monthly salary investing count as dollar-cost averaging?

Yes, but it is not a choice between strategies. When money arrives monthly, investing it monthly is the only option; the lump-sum question only arises when you already hold the whole amount.

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