First day of last menstrual period
Cycle length (days)
Free online pregnancy due date calculator: estimate your due date, conception date, and current pregnancy week using Naegele's rule. Track your trimester and pregnancy progress. Mac OS 9 retro style.
Enter the first day of your last menstrual period (LMP) using the date input. This is the starting point for calculating your due date using Naegele's rule.
The standard cycle is 28 days, but you can adjust this between 20 and 45 days. The calculator automatically adjusts the due date calculation based on your cycle length.
Click 'Calculate Due Date' to see your estimated due date, conception date, current weeks pregnant, and trimester. The calculator updates instantly whenever you change the inputs.
Q: How accurate is the due date calculation?
A: Naegele's rule estimates the due date at 40 weeks (280 days) from the first day of your LMP. It is about 80% accurate within 10 days. Only about 5% of babies arrive exactly on their due date, so use this as a general guideline.
Q: What if I have irregular cycles?
A: For irregular cycles, the calculation becomes less precise. You can adjust the cycle length in the calculator, but we recommend consulting your healthcare provider for a more accurate due date using ultrasound measurements.
Q: When should I see a doctor after a positive test?
A: Most healthcare providers recommend scheduling your first prenatal appointment between 8-12 weeks of pregnancy. Earlier visits may be recommended if you have existing health conditions or pregnancy complications.