For educational and tracking purposes only. Results are estimates and are not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional.
Calculator tool
How this calculator works
Use the explanation to understand the formula, assumptions, and practical limits behind the calculator result.
What Dating Source You Can Use
This calculator can estimate pregnancy timing from:
- First day of the last menstrual period (LMP)
- A known due date
- Conception date
- Ultrasound date plus gestational age
- IVF embryo-transfer date
How LMP Dating Works
For LMP dating, the calculator starts from the first day of the last period, assumes a 28-day cycle baseline, and adjusts when a different average cycle length is entered. That is useful for planning, but it is still an estimate.
Why Due Dates Are Not Exact
A due date is a best estimate, not a guaranteed birth date. Cycle variation, uncertain LMP, embryo transfer details, and ultrasound timing can all change dating. Early ultrasound is often important when dates are uncertain.
What the Result Can and Cannot Do
The tool can organize timing, trimester, and milestones. It cannot confirm pregnancy viability, replace prenatal care, or resolve conflicting clinical dating information.
Frequently asked questions
Which dating method should I choose?
Use the most reliable information you have. If there is a clinician-confirmed ultrasound or IVF transfer date, that may be more useful than a guessed LMP. If dates conflict, follow the medical team handling the pregnancy.
Why can my due date differ from another calculator?
Different tools may assume different cycle lengths, use different starting dates, or apply different IVF and ultrasound rules. Even correct methods can produce slightly different estimates when the inputs differ.
Does the calculator confirm that everything is progressing normally?
No. It only estimates dates. Symptoms, growth, viability, and complications require clinical assessment.
Why is a due date still only an estimate?
Because actual ovulation, implantation, and delivery timing vary. A due date is a planning anchor, not a promise that labor will happen on that exact day.
