Pregnancy Due Date Calculator

An estimated arrival date anchors nearly every decision in the months ahead, from booking prenatal appointments to spacing out the health checks that fall across each trimester in 2026. The estimate can be built from whichever date you have on hand: your last menstrual period, the date of conception, or an IVF transfer. Each path leads to a due date you can plan around well before delivery.

For last menstrual period dates, the standard approach is Naegele's Rule, which adds 280 days, or 40 weeks, to the first day of your last period. A known conception date instead adds 266 days, or 38 weeks, from the estimated moment of fertilization. IVF transfers start from that same 266 days but subtract the embryo's age at transfer, so a 5-day blastocyst, for example, adds 261 days to the transfer date.

Due dates are projections, not appointments, and only about 5% of babies actually arrive on the predicted day. Irregular periods can throw off the LMP method in particular, which is why confirming the estimate with your healthcare provider matters. The date is a tool for organizing the months ahead rather than a substitute for medical guidance.