DCA vs Lump Sum Calculator

• Compares investing everything now with equal monthly installments, with the waiting cash earning the rate you enter.
• Tests four hypothetical markets (steady growth, early crash, late crash, volatile and sideways) so you can see when each approach wins.
• Shows the break-even: in steady growth the lump sum wins only if the market return is above the cash rate.
• Explains Vanguard's research, which found lump-sum investing ahead about two-thirds of the time, and why that is not the whole story for every investor.

How to use this calculator

Enter the amount you have to invest, the number of months you would spread it over, the yearly return you expect from the investment, and the interest rate the uninvested cash would earn. Then choose how far ahead to compare. The headline shows who finishes ahead in the steady-growth case and by how much. The table underneath shows the same comparison for four other market paths.

Open Advanced to change how severe the hypothetical crash is and how large the monthly swings are in the volatile path. Try a few combinations. The most useful thing the calculator does is show how the answer changes with the market path, because no one knows which path will happen.

What dollar-cost averaging is

Dollar-cost averaging, or DCA, means investing a fixed amount at regular intervals instead of all at once. Most people already do this without thinking about it: contributing to a 401(k) from every paycheck is DCA by necessity, because the money only arrives as you earn it. The question this calculator answers is a different one. When you already have a lump sum, from a bonus, an inheritance, a home sale or a rollover, should you deliberately hold part of it back and invest it in installments?

The usual argument for doing so is that it reduces the chance of investing everything just before a fall. The usual argument against is that most of the time markets rise, so money held in cash misses growth. The two arguments are both true, and the numbers below show how they trade off.

How the comparison works

Lump sum         = amount x (market growth over the horizon)
DCA installment  = amount / N, invested at the start of months 0, 1 ... N-1
Cash not yet invested earns the cash rate, compounded monthly
DCA value        = invested installments grown with the market + remaining cash
Break-even       = the market return at which the two end level

Both strategies are valued at the end of the period you choose. Taxes, fees and trading costs are ignored, and both strategies start with the same money on the same day. The first installment is invested immediately, so a 12-month DCA is fully invested after the twelfth installment, eleven months from now.

Because the cash earns interest, DCA is not the same as sitting out of the market. If cash pays as much as the market returns, nothing is lost by waiting. That is the break-even: in steady growth, the lump sum finishes ahead exactly when the market return is higher than the cash rate.

A worked example

With $100,000 to invest, a 12-month DCA, a 7% expected market return, 4% on cash and a three-year comparison, the lump sum is worth $122,504 and the DCA is worth $120,783. The lump sum is ahead by $1,721. The cash earned about $1,846 of interest while it waited, but that is less than the extra market growth it missed.

The gap depends on how long you spread the money out. At 6 months the lump sum's lead is $795; at 24 months, compared over five years, it is $4,247. Only 54% of the money is invested on average during the first 12 months of the DCA, which is what costs growth in a rising market and also what protects you in a falling one.

Change the cash rate to 1% and the lump sum's lead grows to $3,250, because waiting costs more. Set the market return equal to the cash rate at 4% and the difference is $0: nothing to choose between them. Drop the expected market return to 3%, below the cash rate, and DCA wins by $530.

The four hypothetical market paths

The table in the results compares the two approaches in four paths. They are shapes built for illustration. They are not historical data and not forecasts. The first three end with exactly the same total market return, so any difference comes only from when the gains and losses arrive.

• Steady growth. The same return every month. Lump sum ahead by $1,721.
• Early crash, then recovery. The market falls 25% over the first six months, then grows faster to reach the same end point. DCA finishes $27,205 ahead, because most of its installments were bought at the bottom.
• Late crash. Growth, then a 25% fall over the last six months, with the earlier growth set so the end point matches the other paths. The lump sum is ahead by $8,363, because the whole amount rode the earlier growth.
• Volatile and sideways. Alternating 5% up and down months with no net gain. The lump sum ends level with the start at $100,000; DCA ends at $99,616, with a lump-sum lead of only $384, because cash interest offsets the swings.

A deeper early fall makes the DCA advantage larger. At a 40% early crash, DCA finishes $52,348 ahead rather than $27,205. The main lesson is that DCA wins in the bad-start scenario and loses in the others. You are not choosing a better strategy, you are choosing which kind of outcome to be exposed to.

What the historical research found

The best-known study is Vanguard's 2012 paper Dollar-cost averaging just means taking risk later, by Anatoly Shtekhman, Christos Tasopoulos and Brian Wimmer. They compared investing a lump sum immediately with spreading it evenly over 12 months, using rolling 10-year periods and a portfolio of 60% stocks and 40% bonds. Lump-sum investing came out ahead in about two-thirds of the periods: 67% in the United States, 67% in the United Kingdom and 66% in Australia. DCA tended to do better when markets were falling.

Vanguard revisited the question in February 2023 in Cost averaging: Invest now or temporarily hold your cash?, by Megan Finlay and Josef Zorn, and again concluded that lump-sum investing came out ahead more often than not, roughly two times in three across the markets studied, and found that longer cost-averaging schedules lowered the cost-averaging result further.

Three cautions apply. First, "two-thirds of the time" means one third of the time DCA won, and the study's average advantage is not a guarantee. Second, the authors describe DCA as suitable for investors mainly concerned with avoiding regret and downside risk. Third, delaying part of your investment is itself a form of market timing. The research does not say DCA is a mistake; it says that on average you pay a cost for the protection it gives.

Risk and regret

The lump sum is the choice with the higher expected result and the wider spread of results. DCA gives up some expected growth in exchange for a narrower range. In the default case the lump sum's biggest lead across the four paths is $8,363, and its biggest shortfall is $27,205. The shortfall is bigger than the lead. That asymmetry is what people are buying insurance against.

Regret matters in practice. An investor who puts a large sum in on Monday and sees it fall 15% by Friday may sell, and the behaviour then costs more than any difference between strategies. If you know you would do that, a staged plan you can stick to can be better than a lump sum you abandon. The reverse is also true: someone who waits for a better moment, and then keeps waiting, loses far more than the DCA cost.

A middle path exists. Some investors put half in now and spread the rest over three to six months. Shorter schedules cost less in expected growth. Whatever you choose, decide the schedule in advance and write it down, so the decision is made once rather than every month.

Choosing a schedule in practice

If you decide to spread the money out, a few practical points make the plan easier to follow. Keep the schedule short: three to twelve months is typical, and each extra month raises the expected cost of waiting. Put the waiting cash somewhere that pays interest and is safe, such as a money market fund or a high-yield savings account, and let the interest count in the comparison, as this calculator does. Automate the installments so that they happen on a fixed date without a decision each month.

Choose the investment before you start. The question of how fast to move in is separate from the question of what to buy, and mixing them leads to delay. If you are unsure about the mix, the asset allocation calculator on this site can help set a target to invest toward.

Finally, think about the size of the sum compared with everything you own. A sum that is small relative to your portfolio matters little either way, and a lump sum is simple. A sum that is most of your net worth, perhaps from an inheritance or the sale of a business, is where the regret argument carries real weight, and where a staged plan may be worth its expected cost.

When each approach makes sense

Lump sum makes more sense when the money is a modest part of your holdings, when your horizon is long, when you would not be rattled by an early fall, and when you are likely to follow through. It also suits cases where cash earns little, because waiting then costs the most.

Spreading it out makes more sense when the sum is large compared with what you have, when the thought of an immediate loss would make you more likely to abandon the plan, or when cash pays a rate close to what you expect from the market so that waiting costs little. It can also suit someone who is new to investing and wants to build comfort with market swings.

Neither is right for everyone. The calculator does not tell you which to choose. It shows what each is likely to cost or save under assumptions you set, so that the choice you make is an informed one.

Assumptions and limitations

• Hypothetical paths. The four market paths are simple shapes, not history and not forecasts. Real markets combine all of them.
• Expected return. A single constant yearly return, which you choose. Real returns vary a lot year to year.
• Cash. Earns a fixed rate, compounded monthly, with no tax. Money market funds and high-yield savings accounts can differ.
• Equal installments. The first is invested immediately. Uneven schedules, such as only investing on dips, are not modelled.
• No taxes or costs. Trading costs, and taxes on cash interest and on any gains, are not included.
• One lump sum. Employer plans that invest each paycheck are DCA by design and are not what is being compared here.
• Not advice. The right choice depends on your goals, your horizon and how you would react to a fall.

Common mistakes

Treating DCA as risk-free. It reduces the chance of a bad entry point but leaves you fully exposed once invested. It does not protect against a long decline.

Holding the cash somewhere that earns nothing. A checking account paying 0% makes DCA cost more than the model suggests. Park waiting money in a money market fund or savings account.

Waiting for a dip. That is market timing, not DCA. A schedule with a fixed end date is.

Stretching DCA over years. Longer schedules mean more of the money sits out of the market for longer, and the expected cost grows.

Skipping installments when markets fall. The lower prices are exactly where the method helps.

Frequently asked questions