Dollar-cost averaging (DCA) is an investment strategy where you invest a fixed amount at regular intervals regardless of price. Instead of trying to time the market, you let the fixed investment amount buy more shares when prices are low and fewer when prices are high. Over time, this smooths out the impact of market volatility and removes the pressure to pick the perfect entry point.
The Concept
Instead of investing a lump sum of $10,000 once, you invest $1,000 monthly for 10 months. When the asset price is $100, your $1,000 buys 10 shares. When the price drops to $80, you buy 12.5 shares. When it rises to $120, you buy 8.33 shares. Your average cost per share is lower than the arithmetic average of prices because you buy more when prices are low.
Worked Example
Suppose you invest $500 monthly in a stock over 6 months:
| Month | Price | Investment | Shares Bought |
|---|---|---|---|
| 1 | $100 | $500 | 5.00 |
| 2 | $85 | $500 | 5.88 |
| 3 | $90 | $500 | 5.56 |
| 4 | $110 | $500 | 4.55 |
| 5 | $95 | $500 | 5.26 |
| 6 | $105 | $500 | 4.76 |
Total invested: $3,000 Total shares: 30.99 Average cost per share: $3,000 / 30.99 = $96.80
The simple average of prices is ($100 + $85 + $90 + $110 + $95 + $105) / 6 = $97.50, but your actual average cost is $96.80 because you bought more shares at lower prices.
Advantages and Disadvantages
Advantages:
- Removes emotion and timing pressure
- Lowers average purchase cost in volatile markets
- Disciplined, easy to automate
- Works well for retirement savings (401k, IRA)
Disadvantages:
- In a rising market, lump-sum investing outperforms DCA
- Regular investment may miss optimal buying opportunities
- Higher transaction costs from frequent purchases
The Psychology
DCA appeals because it reduces regret. You can't pick the absolute bottom or top, but DCA ensures you're never fully invested at the peak. This peace of mind has real value.
Tips
DCA works best with volatile assets or when you have cash trickling in (like a salary). For assets with downward trends, DCA just means you keep buying a declining asset — market outlook still matters. Also, automate DCA to avoid the temptation to skip months or change the amount.
Use our Dollar-Cost Averaging Calculator to model outcomes with different investment amounts and price scenarios.