Select the calculation method that applies to your situation:
- Last Period (LMP). The most common method. Enter the first day of your last menstrual period. The calculator adds 280 days (40 weeks) to arrive at the estimated due date. This works best with a regular 28-day cycle.
- Conception Date. Use this if you know approximately when conception occurred, such as through ovulation tracking or fertility monitoring. The calculator subtracts 14 days to estimate the LMP equivalent, then adds 280 days.
- IVF Transfer. Enter the embryo transfer date and whether it was a Day 3 or Day 5 blastocyst transfer. IVF due dates are the most precise because the fertilization timeline is exactly known.
The calculator shows your estimated due date, your current gestational week if you are pregnant now, and key milestones: end of first trimester (week 13), second trimester (week 27), and third trimester start (week 28).