Due Date Calculator
Work out your estimated due date and how many weeks pregnant you are from the first day of your last period. The tool also shows your trimester and the days remaining.
Calculator
This result is an educational estimate, not a diagnosis. Ask your doctor to interpret it.
What does this mean?
Advice for you
How does this calculator work?
The calculator uses Naegele's rule: due date = first day of last period + 280 days. If your cycle is longer or shorter than 28 days, the date is shifted by the difference.
The American College of Obstetricians and Gynecologists recommends confirming the date with a first-trimester ultrasound, especially if your cycle is irregular or you don't remember the date.
Scientific sources
- ACOG Committee Opinion No. 700: Methods for Estimating the Due Date. Obstet Gynecol. 2017;129:e150–e154.
- Jukic AM, et al. Length of human pregnancy and contributors to its natural variation. Hum Reprod. 2013;28(10):2848–2855.
Frequently asked questions
How accurate is a due date calculator?
It gives a good estimate, but only about 4% of babies are born on the exact day. An early ultrasound is the most accurate.
What if my periods are irregular?
The calculation is less reliable — use the date from your first-trimester scan instead.
When does each trimester end?
The first trimester runs to the end of week 13, the second from week 14 to 27, and the third from week 28 until birth.
Can I fast while pregnant?
It depends on your health and stage of pregnancy. Many pregnant women are advised not to fast, so discuss it with your doctor before Ramadan.