Health & Fitness
Pregnancy Due Date Calculator
Use this due date calculator for an educational estimate. A clinician may date pregnancy differently using ultrasound or medical history.
Estimated due date
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- Estimated conception date
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Student quick launch
Grade planning, algebra checks, and formulas students reach for most.
Study path
Use this calculator with
Follow these when you want the formula behind the answer, a short lesson, or nearby tools in the same topic.
What the pregnancy due date calculator solves
Use this due date calculator for an educational estimate. A clinician may date pregnancy differently using ultrasound or medical history.
Formula
How to use it
- Enter the first day of the last period.
- Enter average cycle length.
- Use the result as an estimate to discuss with a clinician.
How to read the answer
The due date is an estimate, not a guaranteed delivery date.
Common mistakes and edge cases
- Irregular cycles can make LMP dating less reliable.
- Ultrasound dating may differ.
- Seek medical care for pregnancy questions.
Worked examples
28-day cycle
Estimated due date
2027-02-12
Longer cycle
Estimated due date
2027-02-16
Frequently asked questions
Is this a medical due date?+
No. It is an estimate based on LMP and cycle length.
Why 280 days?+
Pregnancy dating commonly counts about 40 weeks from the last menstrual period.
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Last updated: May 8, 2026