Pregnancy Due Date Calculator
Estimate your due date and how far along you are based on your last menstrual period or conception date. Results are estimates, not medical advice.
Estimate your due date and how far along you are based on your last menstrual period or conception date. Results are estimates, not medical advice.
The most common method estimates your due date as 280 days, or about 40 weeks, from the first day of your last menstrual period, a convention known as Naegele's rule. This assumes a regular 28-day cycle with ovulation around day 14. If you know your conception date, the calculator can instead count roughly 266 days forward. Because cycles and ovulation timing vary, the due date is an estimate of the middle of a likely delivery window rather than a fixed appointment, and most babies arrive in the weeks around it.
A due date is a best estimate, not a precise prediction. Only a small minority of babies are born exactly on their due date, and a full-term delivery is considered normal anywhere from about three weeks before to two weeks after it. Factors such as cycle length, time of ovulation, and individual variation all affect timing. Early ultrasound dating is generally more accurate than calculation from the last period, so your healthcare provider may adjust the estimate.
Pregnancy is conventionally divided into three trimesters. The first runs from week 1 to around week 12 and involves early development; the second spans roughly weeks 13 to 27 and is often when many people feel most comfortable; and the third covers about week 28 to birth, as the baby grows rapidly in preparation for delivery. The calculator shows which trimester an estimated date falls in to help you follow your progress.
You can, but the result will be less reliable. The standard calculation assumes a regular 28-day cycle, so if your cycles are longer, shorter, or unpredictable, the estimated date may be off. If you know your conception or ovulation date, using that will improve the estimate. For irregular cycles, an early ultrasound arranged by your healthcare provider is the most dependable way to date the pregnancy.
No. This tool provides general estimates for informational purposes only and does not replace professional medical advice, diagnosis, or monitoring. Pregnancy should be overseen by a qualified healthcare provider who can confirm dating, track development, and address any concerns. Always consult your doctor or midwife for guidance specific to your situation.