Investment Strategy · Visual Examples

What Is Dollar-Cost Averaging?

Invest the same amount every month. Buy more when prices are low, less when prices are high. The simplest strategy that actually works.

How Dollar-Cost Averaging Works

Dollar-cost averaging (DCA) is the strategy of investing a fixed dollar amount at regular intervals, regardless of market conditions. Instead of trying to pick the perfect time to invest (which nobody can do reliably), you invest consistently — every month, every paycheck, every week — no matter what.

The math is elegant: when the market is expensive, your fixed $500 buys fewer shares. When the market is cheap, the same $500 buys more shares. Over time, your average cost per share is lower than the average price per share. You automatically buy more of the bargains and less of the expensive stuff.

DCA Example: $500/Month

Hypothetical example: investing $500/month in an index fund over 6 months during a volatile market.

Month	Share Price	Shares Bought	Total Invested
January	$50	10.0 shares	$500
February	$45	11.1 shares	$1,000
March	$35	14.3 shares	$1,500
April	$30	16.7 shares	$2,000
May	$40	12.5 shares	$2,500
June	$50	10.0 shares	$3,000

Total Invested:

$3,000

Total Shares:

74.6 shares

Average Cost:

$40.21/share

The average price over 6 months was $41.67. But your average cost was $40.21 — because you bought more shares when prices were low. At $50/share in June, your 74.6 shares are worth $3,730 — a 24.3% gain on $3,000 invested.

DCA vs Lump Sum Investing

Academic research (notably a Vanguard study) shows that lump-sum investing beats DCA about 66% of the time over 12-month periods. This is because markets go up more often than they go down — so getting your money invested sooner generally produces better results.

However, DCA wins on psychology. If you invest $100,000 on Monday and the market drops 15% on Tuesday, you have lost $15,000 immediately. Most people cannot handle that emotionally. DCA spreads the risk and reduces the chance of a catastrophically timed entry.

Choose Lump Sum If...

+You have a high risk tolerance
+You will not panic-sell in a downturn
+You understand 66% odds favor lump sum
+You are investing for 10+ years

Choose DCA If...

+You are anxious about investing a large sum
+You want to minimize regret risk
+You earn money monthly (most people)
+The alternative is not investing at all

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How to Set Up Dollar-Cost Averaging

Choose your investment

A low-cost index fund like VTI, VOO, or a target-date fund. Diversified funds work best for DCA because they recover from dips over time.

Set your amount

Pick an amount you can invest consistently every month. $100, $500, $1,000 — whatever fits your budget. Consistency matters more than size.

Automate it

Set up automatic transfers from your bank to your brokerage account, and automatic purchases of your chosen fund. Remove yourself from the decision entirely.

Never stop (especially in downturns)

The biggest DCA mistake is stopping your contributions when the market drops. Downturns are when DCA helps you most — you are buying shares at a discount.

Glen's Take

Dollar-cost averaging is not the mathematically optimal strategy. It is the psychologically optimal strategy. And since humans are emotional creatures, that makes it the best strategy for most people.

The best investment strategy is the one you actually follow. DCA works because it takes willpower out of the equation. You set it up once and your wealth builds automatically — through bull markets, bear markets, pandemics, elections, and everything else.

$500/month in an S&P 500 index fund at 10% average returns grows to $1.1 million in 30 years. Not because of any brilliant strategy. Because of consistency. DCA is the mechanism that enforces that consistency. Use it.

Frequently Asked Questions

What is dollar-cost averaging in simple terms?

Dollar-cost averaging (DCA) means investing a fixed amount of money at regular intervals — like $500 every month — regardless of whether the market is up or down. When prices are high, your fixed amount buys fewer shares. When prices are low, the same amount buys more shares. Over time, this lowers your average cost per share.

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

Mathematically, lump-sum investing beats DCA about two-thirds of the time because markets go up more often than they go down. However, DCA is psychologically easier — most people cannot stomach investing a large sum right before a 20% market drop. DCA reduces regret risk and is the right choice if the alternative is not investing at all.

Does dollar-cost averaging really work?

Yes. DCA works because it enforces disciplined, consistent investing. It removes the temptation to time the market (which almost no one can do successfully). The most important factor in building wealth is not timing — it is time in the market. DCA gets you invested consistently, which is what matters most.

How often should I dollar-cost average?

Monthly is the most common and practical interval. Many people align DCA with their paycheck — investing on the 1st or 15th of each month. Weekly or bi-weekly DCA provides slightly better results in theory but the difference is negligible. The key is consistency, not frequency.

What should I invest in with dollar-cost averaging?

Low-cost index funds are ideal for DCA. VTI (total U.S. market), VOO (S&P 500), or a target-date retirement fund are excellent choices. DCA works best with diversified funds that trend upward over the long term. Do not use DCA on individual stocks — a single company can go to zero.

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