Pregnancy Due Date Calculator

Calculate your expected due date, current week of pregnancy and key milestones.

Enter your last menstrual period date to calculate your due date

How due date is calculated

Naegele's rule is the standard method for calculating the estimated due date (EDD). It assumes a 28-day menstrual cycle and ovulation on day 14.

Naegele's Rule
EDD = LMP + 280 days (40 weeks)
Example: LMP = 1 January 2025 → EDD = 8 October 2025. Alternatively: add 1 year, subtract 3 months, add 7 days.
From Conception Date
EDD = Conception date + 266 days (38 weeks)
Conception is typically 14 days after LMP in a 28-day cycle, hence 280 − 14 = 266 days from conception to EDD.

Frequently asked questions

How accurate is the LMP-based due date calculation?

The LMP method assumes a perfect 28-day cycle with ovulation on day 14. In reality, cycle lengths vary (21–35 days is normal) and ovulation timing varies. An early ultrasound (6–12 weeks) provides a more accurate due date and is recommended for all pregnancies.

What is a full-term pregnancy in India?

A pregnancy is considered full term at 39–40 weeks gestation. Early term is 37–38 weeks, late term is 41 weeks, and post-term is 42+ weeks. Most Indian hospitals aim to deliver between 39–41 weeks unless there are complications.

What are the three trimesters of pregnancy?

First trimester: weeks 1–13 (organ formation, highest miscarriage risk). Second trimester: weeks 14–27 (foetal growth, anatomy scan at 20 weeks). Third trimester: weeks 28–40+ (rapid weight gain, lung maturation, preparation for birth).

When is the anomaly scan done in India?

The detailed anomaly scan (Level 2 ultrasound) is typically done between 18–20 weeks gestation to check foetal anatomy and growth. Most government hospitals and private clinics in India offer this as part of routine antenatal care. The PNDT Act governs ultrasound use in India.

What if my cycle is longer or shorter than 28 days?

Adjust the LMP calculation by the difference from 28 days. If your cycle is 35 days (7 days longer), ovulation occurred 7 days later, so add 7 days to the calculated EDD. If your cycle is 21 days (7 days shorter), subtract 7 days. An early dating ultrasound eliminates this uncertainty.