Dollar-cost averaging changes the path
Monthly investing lowers the importance of picking a single perfect entry date. It spreads purchase prices across time and usually makes the investing process easier to sustain.
For a calculator, this means the final number should come from each contribution date separately, not from one blended CAGR shortcut.
Model the schedule clearly
Users trust a calculator more when it shows the contribution schedule, the trade-date adjustment rule, and the total amount invested.
These details also help AI search systems summarize the methodology accurately.