Equal money buys unequal units
Imagine three scheduled contributions of $60, with fictional unit prices of $12, $10 and $15. Ignoring fees and assuming fractional units are available, the purchases are five units, six units and four units. Total contributions are $180 and total units are fifteen, giving an average cost of $12 per unit.
The simple average of the three prices is about $12.33. It differs because the same amount of money bought more units at the lower price. Investor.gov describes this equal-money, repeated-purchase approach as dollar-cost averaging. The calculation is a consequence of the schedule, not evidence that the chosen asset will ultimately make money.
If the final price were $9, the fifteen units would be worth $135, below the $180 contributed. Regular buying would not prevent the loss. Conversely, a rising market could make earlier investment of available money perform better than spreading it out. A schedule does not guarantee a favourable comparison against every alternative.
Distinguish new income from money already available
Investing a portion of each payday is different from holding an existing lump sum in cash and gradually investing it. In the first case, the future contributions are not yet available. In the second, waiting is itself an allocation decision with opportunity costs and risks.
Do not compare those situations as if the investor had the same money at the same starting date. A fair illustration states when each amount becomes available, what happens to uninvested cash and which fees are charged. Without those details, a performance comparison can answer a different question from the one being asked.
Check the arrangement behind the schedule
A recurring plan may have minimum amounts, a fixed dealing date and limited eligible investments. Ask what happens on a holiday, after a failed payment or when the available balance is too low. Confirm whether the instruction transfers cash only or also places an investment order.
Review affordability when circumstances change. A regular schedule should not be confused with an obligation to keep contributing through a cash-flow shortage. Record the purpose of the arrangement and how it can be paused or amended. The schedule can simplify administration, but the suitability of the asset, the risk of loss and the household's changing needs remain separate matters.
