I've been trying to figure out exactly how due date calculators work and what they actually track week by week. I've seen various online calculators, but I'm not sure how accurate they are or how closely they align with what happens in a typical pregnancy. Do these calculators just start counting from the last menstrual period, or do they adjust based on conception dates if known? Also, how do they account for the differences in individual cycle lengths and variations in early development? It would be great to hear some experiences from those who have used them, and any insights on how closely they matched up with your actual delivery date.