Pregnancy Due Date Calculator
Estimate your due date using LMP, conception date, or IVF transfer date with weekly milestones and trimester tracking.
Pregnancy due date calculator
Updates as you typeEducational — not medical advice. Always confirm with your healthcare provider.
Examples
How It Works
Last Menstrual Period (LMP): The most common method. It adds 280 days (40 weeks) to the first day of your last menstrual period. This is the standard Naegele's rule used by most healthcare providers.
Conception Date: If you know your conception or ovulation date, the calculator adds 266 days (38 weeks). This method is more precise when the conception date is known, as it removes the assumption of a 14-day follicular phase.
IVF Transfer Date: For IVF pregnancies, the calculator accounts for the embryo's age at transfer. For a 5-day blastocyst transfer, it adds 261 days (266 − 5). For a 3-day cleavage-stage transfer, it adds 263 days (266 − 3).
The calculator also shows your current gestational week, trimester, a visual progress bar, baby size comparisons (fruit/vegetable analogies), and upcoming developmental milestones.
Tips & Best Practices
Frequently Asked Questions
How accurate is the due date calculation?
The LMP method is the clinical standard but assumes a regular 28-day cycle. Actual delivery dates vary — about 80% of babies are born between 38 and 42 weeks. Your healthcare provider may adjust the date based on ultrasound measurements.
What's the difference between gestational age and fetal age?
Gestational age counts from the first day of your last period (LMP) and is about 2 weeks longer than fetal age, which counts from conception. Medical professionals typically use gestational age (40 weeks total).
Why does the IVF calculation need the embryo age?
IVF embryos are cultured for either 3 or 5 days before transfer. Since the embryo already has that age at transfer, the calculator subtracts it from the standard 266-day post-conception period to get the correct due date.