Pregnancy Due Date Calculator
Estimate due date using LMP, conception, ultrasound, or IVF transfer methods.
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Result
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Formula
The calculator supports multiple method paths and estimates weeks remaining and trimester.
Worked Example
How Pregnancy Due Dates Are Estimated
- LMP method: add 280 days to the first day of your last menstrual period. This is the standard obstetric dating method
- Conception method: add 266 days (38 weeks) from the known or estimated date of conception
- Ultrasound method: the most accurate early in pregnancy, especially when done before 12 weeks
- IVF method: add 266 days minus embryo age at transfer for the most precise calculation in IVF pregnancies
Only about 5% of babies are born on their exact due date. Most arrive within 2 weeks before or after. Always consult your healthcare provider for personalized guidance.
You can also calculate changes using our Ovulation Calculator, IVF Calculator or Gestational Age Calculator.
Frequently Asked Questions
Is this a medical diagnosis?
No. This is a planning estimate. Due dates are approximations, and only about 5% of babies arrive on the exact predicted date. Consult your healthcare provider for medical guidance.
Which method is most accurate?
First-trimester ultrasound dating is generally the most accurate. The LMP method is the standard starting point but can be off if cycles are irregular or the exact LMP date is uncertain.
Can my due date change?
Yes. Your healthcare provider may adjust your due date based on ultrasound measurements, especially if there is a significant difference from the LMP-based estimate.
What is the IVF transfer method?
For IVF pregnancies, the due date is calculated from the known transfer date minus the embryo age at transfer. This is the most precise method because both dates are medically documented.
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