How is the due date calculated from LMP?

The due date from LMP (Last Menstrual Period) is calculated using Naegele's rule: add 280 days (40 weeks) to the first day of the last menstrual period. This assumes a 28-day cycle with ovulation on day 14.

How accurate is the LMP due date calculator?

LMP-based calculation is accurate to within 1-2 weeks for women with regular 28-day cycles. For irregular cycles, ultrasound dating in the first trimester (CRL measurement) is more accurate.

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Pregnancy Due Date Calculator

EDD Calculator · Week by Week · India · LMP · IVF · Ultrasound

LMP Based IVF / FET Ultrasound CRL Conception Date Week by Week Scan Reminders

How would you like to calculate?

💡 Enter the first day of your last menstrual period. This is the most common method — your due date will be 280 days (40 weeks) from this date.

First Day of LMP

Cycle Length (days)

💡 Enter the date of conception or IVF retrieval. Your due date will be 266 days (38 weeks) from this date.

Conception / IVF Retrieval Date

💡 Enter your ultrasound date and the gestational age given by the sonologist (in weeks and days). This method is most accurate in the first trimester.

Date of Ultrasound

Gestational Age — Weeks

Gestational Age — Days

💡 Enter your embryo transfer date and select the embryo age at transfer. For Day 3 transfers, due date = transfer date + 263 days. For Day 5 (blastocyst), due date = transfer date + 261 days.

Embryo Transfer Date

Embryo Age at Transfer

Estimated Due Date (EDD)

Pregnancy progress Week 0 of 40

Week 1 T2 (Week 14) T3 (Week 28) Week 40

Trimester Breakdown

Key Scans & Tests — India Schedule

Baby's Week-by-Week Development

Common Symptoms by Trimester

⚠️ This is an estimated due date. Only ~5% of babies are born on their exact EDD. Due dates may be revised by your obstetrician based on ultrasound findings. Always follow your doctor's guidance.

How Is the Due Date Calculated?

LMP method (Naegele's Rule): Add 280 days (40 weeks) to the first day of your last menstrual period. This is adjusted automatically for cycle lengths other than 28 days.

Conception date: Add 266 days (38 weeks) to the date of conception or egg retrieval.

Ultrasound (CRL): The sonologist measures the crown-rump length of the baby and assigns a gestational age. This method is most accurate between 7–13 weeks.

IVF transfer: For Day 5 blastocyst transfers, the equivalent LMP is calculated as transfer date minus 19 days, giving a due date 261 days after transfer.

Important Scans During Pregnancy in India

Dating scan (7–10 weeks), NT scan (11–14 weeks) for chromosomal screening, anomaly scan (18–20 weeks) to check fetal anatomy, growth scan (28–32 weeks), and a term scan (36–38 weeks) before delivery.

Frequently Asked Questions

How accurate is the LMP-based due date?

Accurate within 1–2 weeks for regular 28-day cycles. For irregular cycles, first trimester ultrasound dating is more reliable.

When are the important scans during pregnancy in India?

Dating scan at 7–10 weeks, NT scan at 11–14 weeks, anomaly scan at 18–20 weeks, growth scan at 28–32 weeks, and term scan at 36–38 weeks.

What is full term pregnancy?

Full term is 39–40 weeks. Early term is 37–38 weeks. Late term is 41 weeks. Post-term is 42+ weeks. Most doctors in India plan delivery by 40–41 weeks.

How is IVF due date different from LMP due date?

For Day 5 blastocyst transfer, the EDD is calculated as transfer date + 261 days (equivalent to LMP – 19 days). The LMP-based calculation would overestimate gestation since fertilisation is precisely known in IVF.