Pregnancy due date calculator
Your estimated due date, how far along you are and the key dates ahead.
28 days is typical. Longer cycles move the due date later.
Estimated due date
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Choose a method and enter the date.
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How to calculate your due date
- 1
Choose what you know: last period, conception date, IVF transfer, a scan or the due date.
- 2
Enter the date, and your cycle length or the scan measurement if asked.
- 3
See your due date, how many weeks pregnant you are and your trimester.
- 4
Check the dates of the usual scans and milestones.
Your due date, from what you know
Doctors date a pregnancy from the first day of your last menstrual period (LMP), and the due date is 40 weeks (280 days) after it. The calculator works this out from whichever date you have:
- Last period: LMP + 280 days, adjusted for your cycle length. A 35-day cycle moves the due date a week later.
- Conception date: conception + 266 days.
- IVF transfer: a day-5 blastocyst transfer + 261 days; a day-3 transfer + 263 days.
- Ultrasound: the scan date minus the age measured at the scan, then + 280 days.
- Known due date: to see how far along you are today.
A due date calculator and pregnancy week calculator: find your EDD (estimated date of delivery) and how many weeks pregnant you are.
Example
With a last period starting on 1 January 2026 and a 28-day cycle, the due date is 8 October 2026. On 11 April 2026 you’d be 14 weeks and 2 days pregnant, at the start of the second trimester.
Weeks and trimesters
Weeks are written as completed weeks plus days, so “14+2” means 14 weeks and 2 days. Because they’re counted from the last period, you’re already about 2 weeks pregnant at conception. The first trimester runs to the end of week 13, the second to the end of week 27, and the third from week 28 to birth.
Key dates
The calculator lists the dates of the usual checks: the dating and NT scan (11–13 weeks), the anatomy scan (18–22 weeks) and the glucose test (24–28 weeks), plus when you reach early term (37 weeks) and full term (39 weeks). Schedules vary by country and doctor, so follow your own care plan.
How exact is it?
Only a few babies arrive on their due date; most come within two weeks either side. An early ultrasound is the most accurate way to date a pregnancy, so your doctor may change your date after one.
Plan the months ahead with the ovulation calculator before pregnancy and the baby age calculator after. This page gives general information, not medical advice.
Frequently asked questions
How is the due date calculated?
By Naegele’s rule: 280 days (40 weeks) after the first day of your last period, assuming a 28-day cycle. A last period on 1 January 2026 gives a due date of 8 October 2026. Longer cycles move it later.
How many weeks pregnant am I?
Pregnancy weeks are counted from the first day of your last period, not from conception, so at conception you’re already about 2 weeks pregnant. The calculator shows weeks and days as doctors write them.
How accurate is the due date?
It’s an estimate. Only a few babies arrive on the due date; most come within two weeks either side. An early ultrasound is the most accurate way to date a pregnancy, and your doctor may change the date after one.
How does it work for IVF?
Choose the transfer type. A day-5 blastocyst transfer gives a due date 261 days after the transfer, a day-3 transfer 263 days after.