Due Date Calculator
When will you meet your baby? Get a planning estimate from whatever you know: last period, conception day, IVF transfer, or a due date you'd like to explore.
A quick planning estimate of when you’ll likely meet your baby. Choose the method that fits what you know, your prenatal provider will confirm the official date.
The first day of bleeding, not the last.
Most cycles run 21–35 days; 28 is the classic average.
How this works
Last period: Naegele’s rule, due date = first day of your last period + 280 days, adjusted for your cycle length (ACOG’s dating guidance).
Conception date: due date = conception + 266 days.
IVF: transfer date + 263 days (day-3 embryo) or + 261 days (day-5 blastocyst).
Source: ACOG Committee Opinion 700, “Methods for Estimating the Due Date.” Only about 1 in 20 babies arrives on the exact due date, think of it as the center of a window, not an appointment.
Sources & method
Due-date and gestational-age math follows ACOG Committee Opinion 700, “Methods for Estimating the Due Date” (Naegele’s rule and ART-based dating). Trimester boundaries follow ACOG patient-education definitions. All results are planning estimates, your prenatal healthcare provider determines your clinical due date.
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