Pregnancy Due Date Calculator
Calculate your due date and how far along you are, worked out the way clinicians do.
- Runs on your device
- No watermark
- Free, no signup needed
- Available offline
An estimate for information only, not medical advice. Your doctor or midwife may change your due date after an ultrasound scan, so follow their advice.
How to use it
- Choose what to count from: your last period, conception or an IVF transfer.
- Enter the date.
- See your estimated due date, weeks pregnant and trimester dates.
Questions
How is the due date calculated?
With Naegele’s rule: 280 days (40 weeks) after the first day of your last menstrual period. From a conception date it is 266 days later. For IVF, ACOG adds 261 days to a day-5 embryo transfer date and 263 days to a day-3 transfer date.
Why does pregnancy start before conception?
By convention, pregnancy is dated from the first day of the last period, which is about two weeks before ovulation and conception in a 28-day cycle.
Can my due date change?
Yes. ACOG recommends confirming the date with an ultrasound early in pregnancy, and your doctor or midwife may adjust it if the scan and your dates differ.
When do the trimesters start?
The second trimester starts at week 14 and the third at week 28, counted from the first day of the last period.
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