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Investment
Dollar-cost averaging means investing the same amount regularly regardless of market conditions — and it works.
By FreeCalculators Editorial · Published 2026-09-01 · Updated 2026-09-04 · 5 min read · 1,026 words
Dollar-cost averaging means investing a fixed dollar amount at fixed intervals regardless of price. Because a fixed sum buys more shares when prices are low and fewer when they are high, the average cost per share comes out below the average price over the period. For anyone investing from a paycheck it is not a strategy choice at all — it is the only mechanism available, and it happens to be a good one.
The effect is arithmetic, not behavioural. A fixed dollar amount divided by a lower price buys proportionally more shares, so low-price periods receive a larger share weight in your final holding. The result is a harmonic mean rather than an arithmetic mean, and the harmonic mean is always the lower of the two when prices vary.
Four months of a fixed 1,000 dollar purchase (2026)
Month 1: price $50 -> 20.00 shares
Month 2: price $40 -> 25.00 shares
Month 3: price $25 -> 40.00 shares
Month 4: price $40 -> 25.00 shares
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Total invested $4,000 110.00 shares
Average price paid = (50+40+25+40) / 4 = $38.75
Average cost/share = $4,000 / 110 = $36.36
Advantage = $2.39 per share, 6.2%
Value at month 4 price of $40
= 110 x $40 = $4,400 on $4,000 investedThe 6.2% advantage exists because prices varied. In a market that rose smoothly every month, dollar-cost averaging would produce a higher average cost than a single purchase at the start — which is exactly the lump-sum comparison below.
These are different questions and they get conflated constantly. Investing each paycheck as it arrives is dollar-cost averaging by necessity. Choosing to spread an existing lump sum over twelve months is a deliberate decision to hold cash, and cash — which earns whatever short-term rate the Federal Reserve policy path implies — has a lower expected return than the portfolio you are heading toward.
| Situation | Better approach | Why | Cost of the alternative |
|---|---|---|---|
| Monthly savings from salary | Invest each month as it arrives | No cash is idle at any point | None — this is the only option |
| Inherited or bonus lump sum, long horizon | Invest immediately | Markets rise in most years; cash earns less | Roughly 1% to 2% expected, on average |
| Lump sum, investor anxious about timing | Spread over 3 to 6 months | Lowers regret risk and the chance of an early exit | Small expected cost, real behavioural gain |
| Lump sum needed within 3 years | Do not invest it in equities at all | A 30% decline would derail the goal | Potentially the goal itself |
| Rebalancing proceeds | Reinvest immediately | The money is already committed to the market | Time out of the market |
| Windfall during a crash | Invest to target weights immediately | Prices are already lower than your average | Waiting for a bottom that is unmarked |
The third item is where the strategy usually fails. Stopping contributions during a downturn is far more common than selling, and it is nearly as costly: those are the months where a fixed dollar amount buys the largest number of shares.
Project a monthly schedule with the SIP calculator, and if you are deciding what to do with an existing lump sum, compare both paths in the lump sum vs DCA calculator before spreading it out. The expected cost of waiting is usually smaller than investors fear and larger than zero.
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How this guide was created
This guide was written and reviewed by FreeCalculators Editorial, drawing on published formulas, official government sources, and real calculator outputs from our 4 calculators in this category. Every claim is sourced; every formula is auditable. Read our review policy.