Pregnancy Due Date Calculator
Estimate your baby's due date and trimester dates from the first day of your last menstrual period.
Show solution steps
What is the Pregnancy Due Date Calculator?
A due date calculator estimates when your baby is likely to arrive, roughly 40 weeks from the first day of your last period. It's an estimate — only about 1 in 20 babies arrive exactly on the due date.
How to Calculate
Naegele's rule: due date = LMP + 280 days (40 weeks). The second trimester begins around week 13 and the third around week 27.
Formula
Due date = first day of last period + 280 days
How to Use
- Enter your details in the fields above.
- The result updates instantly as you type.
- Use Copy, Print or Download PDF to save your result.
Frequently Asked Questions
How accurate is the due date?
It's an estimate assuming a regular 28-day cycle. Your doctor may adjust it based on an ultrasound. Always follow professional medical advice.
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