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Lump Sum vs Dollar Cost Averaging Calculator
Got a windfall, bonus or inheritance to invest? Compare putting it all in today with spreading it over several months. The calculator runs thousands of simulated markets using your expected return and volatility, then shows how often each approach wins, the expected values and how each one fares in a bad market.
Last updated:
Your money
$
months
Equal monthly buys; the first one is made today.
% / yr
Savings or money-market rate earned by the money not yet invested.
years
Must be at least as long as the DCA period.
Market assumptions
%
Long-run average you assume, not a forecast.
%
Broad stock index ≈ 15–20%; bonds ≈ 4–7%.
Enter your values to see the result.
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How to use the Lump Sum vs Dollar Cost Averaging Calculator
Enter the amount you have to invest and how many months you would spread it over.
Set the cash yield the waiting money earns and how many years to compare after.
Enter your market assumptions: expected yearly return and volatility, or tap a preset.
Press Compare strategies to run the simulations.
Read the win rate, then check the bad-market row to see how much DCA cushions a drop.
What the calculator compares
Both strategies start with the same amount A and end at the same date. The lump sum buys everything on day one. Dollar cost averaging (DCA) buys A ÷ N at the start of each of the next N months and keeps the rest in cash earning your cash yield.
Lump sum = A × gH · DCA = Σ (A ÷ N) × gH − k + cash interest
Here g is the expected monthly growth factor, (1 + yearly return)1/12, and H is the horizon in months. Those formulas give the expected values. Real markets are bumpy, so the calculator also simulates thousands of random monthly paths with your volatility and counts how often each approach finishes ahead.
How the trade-off usually looks
Situation
Usually favored
Why
Expected return well above the cash yield
Lump sum
More time in the market on average
Cash yields about as much as the investment
DCA (little cost)
Waiting gives up almost nothing and lowers timing risk
Very volatile asset
Closer call
Wider range of outcomes; DCA protects more in bad paths
You would panic-sell after a quick drop
DCA
Staying invested matters more than the last bit of return
Long horizon (10+ years)
Lump sum, smaller gap
A few months of averaging matters less over decades
Tips
Look at the 10th percentile row, not just the win rate. It shows how much DCA softens a bad start.
Use a realistic, conservative expected return. Higher assumed returns make the lump sum look stronger.
If you choose DCA, automate the monthly buys so the plan is followed even when markets are falling.
Educational estimate only, not investment advice. Simulations use a simple lognormal model with no fees or taxes; real markets can behave differently.
Frequently asked questions
Is lump sum investing better than dollar cost averaging?
On average, usually yes. When the expected return of the investment is higher than the yield on cash, money invested sooner has more time to grow, so a lump sum tends to finish ahead in most simulated and historical periods. Dollar cost averaging wins when prices fall during the averaging period.
Why use dollar cost averaging at all, then?
It reduces regret and the risk of putting everything in right before a drop. If investing a large sum at once would keep you from investing at all, or would make you sell in a panic after a decline, spreading it out can be the better plan for you even if it gives up some expected return.
How does the simulation work?
Each simulated market draws a random return every month from a lognormal distribution whose average matches your expected return and whose spread matches your volatility. Both strategies face exactly the same market path, so the comparison is fair. The random seed is fixed, so the same inputs always give the same results.
What volatility should I enter?
Volatility is the yearly standard deviation of returns. Broad stock indexes have historically been around 15 to 20 percent, a balanced stock and bond mix roughly 8 to 12 percent and high-quality bonds about 4 to 7 percent. Single stocks and crypto can be far higher. Past figures are only a rough guide.
Does the cash yield matter?
Yes. Money waiting to be invested earns the cash rate instead of the market return. The smaller the gap between the two, the less dollar cost averaging costs you. If cash yields as much as you expect from the market, DCA gives up nothing on average and reduces risk.
How long should a DCA period be?
Longer periods leave more money in cash for longer, which lowers expected value but reduces timing risk. Many people who choose to average in use 3 to 12 months. Try several periods here to see how the win rate and the bad-market result change.
Is this the same as investing from every paycheck?
No. Investing part of each paycheck is simply investing money as you earn it, which is the right default. This calculator is about money you already have in hand and could invest all at once.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.