Printed on 2/13/2026
For informational purposes only. This is not medical advice.
This pregnancy due date calculator uses Naegele's rule to estimate your expected delivery date (EDD) from the first day of your last menstrual period (LMP). It adds 280 days (40 weeks) to the LMP date and shows your current gestational age, trimester, and days remaining. Naegele's rule assumes a 28-day menstrual cycle with ovulation on day 14.
Formula: EDD = LMP + 280 days (Naegele's Rule)
Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.
Calculate the Bishop Score to assess cervical favorability for labor induction. Predicts likelihood of successful vaginal delivery.
ObstetricsCalculate the Apgar Score to quickly assess newborn health at 1 and 5 minutes after birth. Evaluates appearance, pulse, grimace, activity, and respiration.
The due date is calculated using Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). This assumes a 28-day cycle with ovulation at day 14. Only about 5% of babies are born on their exact due date — most deliver within 2 weeks before or after.
If your cycle is regularly longer or shorter than 28 days, your ovulation date differs from the assumed day 14. Adjustments can be made: add or subtract the difference from 28 days. Ultrasound dating in the first trimester is often more accurate for irregular cycles.
First trimester: weeks 1–12 (organ formation). Second trimester: weeks 13–27 (rapid growth, movements felt). Third trimester: weeks 28–40 (final development, preparation for birth). Each trimester has different milestones and prenatal care recommendations.
Naegele's rule is accurate to ±2 weeks for women with regular 28-day cycles. First-trimester ultrasound is the most accurate dating method (±5–7 days). Only about 5% of babies arrive on the exact due date. A 'term' pregnancy is 37–42 weeks.