Free tool

Pregnancy Due Date Calculator

Estimate your due date, see how far along you are today, and map the key milestones of the weeks ahead.

What happens after the estimate

Once pregnancy is confirmed, the first port of call is a dating ultrasound between 8 and 12 weeks — it measures the baby and sets the definitive due date. The NT scan (11–14 weeks) and the anomaly scan (18–22 weeks) follow as the two big checkpoints of the first half.

Folic acid supplementation is recommended from before conception through the first trimester to support neural-tube development, and B12 alongside it supports nerve health and red-cell formation. Any supplementation during pregnancy should be on your gynecologist's advice.

Common questions

How is the due date calculated?

By Naegele's rule: 280 days (40 weeks) from the first day of the last menstrual period, adjusted for cycle length. If you know the conception date, the estimate is 266 days from conception. Only about 4–5% of babies arrive exactly on the due date — most arrive within a week either side.

Why does cycle length change the estimate?

The 40-week rule assumes ovulation on day 14 of a 28-day cycle. A longer cycle usually means later ovulation, so the due date shifts forward; a shorter cycle shifts it back.

Which is more accurate — LMP or an ultrasound?

A first-trimester dating ultrasound (crown-rump length) is the most accurate way to date a pregnancy and is what your gynecologist will rely on. Calculator estimates are a planning aid until that scan.

What counts as full term?

37 completed weeks is considered early full term, 39–40 weeks full term. Delivery before 37 weeks is preterm and needs specialist care.

This tool is for general information and is not medical advice, diagnosis, or treatment. Always confirm dates and care with a qualified gynecologist.

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