Due Date Calculator
Find your estimated delivery date and important pregnancy milestones.
Estimated Due Date
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Conception Date (approx)
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Weeks Remaining
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Pregnancy Timeline
Due Date Calculation Method
Standard pregnancy is 40 weeks (280 days) from the first day of your last menstrual period. This is called Naegele's rule and is the most common method used by providers.
Why Due Dates Are Estimates
Only about 5% of babies arrive on their exact due date. Normal range is 37-42 weeks. Your provider may adjust the date based on ultrasound measurements or conception timing.
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Frequently asked questions
How accurate is a due date calculator?
Due date calculators using LMP are accurate within 7-14 days. Only 5% of babies are born on their exact due date. First-trimester ultrasound is more precise.
What is Naegele's rule for due date?
Naegele's rule: LMP date plus 280 days (40 weeks). This assumes 28-day cycles and conception on day 14. Our calculator applies this automatically.
How do I calculate due date without LMP?
If LMP unknown, use IVF transfer date plus 266 days, or ultrasound measurements. Our calculator requires LMP for best accuracy.
Can I calculate due date from ovulation?
Yes. Ovulation date plus 266 days equals estimated due date. Since ovulation is typically day 14 after LMP, this aligns with Naegele's rule.
What is the average pregnancy length?
Full term is 40 weeks from LMP (38 weeks from conception). Normal range is 37-42 weeks. Babies can be healthy outside this range with medical support.