Enter Pregnancy Details
Example Data Table
| Scenario | Method | Reference input | Cycle or transfer detail | Example due date result |
|---|---|---|---|---|
| Regular cycle pregnancy | LMP | 2026-01-05 | 28-day cycle | 2026-10-12 |
| Longer cycle planning | LMP | 2026-01-05 | 32-day cycle | 2026-10-16 |
| Known conception | Conception date | 2026-02-01 | Standard dating | 2026-10-25 |
| Embryo transfer case | IVF transfer | 2026-02-10 | Day 5 embryo | 2026-10-29 |
Formula Used
1) LMP method: Estimated due date = LMP + 280 days + (cycle length - 28 days).
2) Conception method: Estimated due date = conception date + 266 days. Estimated LMP = conception date - 14 days.
3) Due date method: Estimated LMP = due date - 280 days. Estimated conception = due date - 266 days.
4) IVF transfer method: Estimated due date = transfer date + (266 - embryo age in days). Estimated LMP = transfer date - (14 + embryo age).
5) Gestational age today: Days pregnant = today - estimated LMP. Weeks = floor(days pregnant / 7). Remaining days = days pregnant mod 7.
6) Trimester boundaries: First trimester ends at 13 weeks 6 days, second ends at 27 weeks 6 days, and third continues to delivery.
How to Use This Calculator
- Choose the dating method that matches the information you know best.
- Enter your reference date. Add cycle length only when using the LMP method.
- Select the embryo age if your pregnancy started with IVF transfer.
- Press the calculate button to display the result above the form.
- Review the due date, gestational age, trimester changes, and milestone windows.
- Download the summary as CSV or PDF for records, visits, or planning notes.
- Confirm important dates with your healthcare team, especially after an ultrasound.
Frequently Asked Questions
1. Which method is usually most accurate?
Early ultrasound dating is often the strongest clinical reference. Before that, an accurate LMP or IVF transfer date gives a solid estimate for planning milestones and appointments.
2. Why does cycle length change the due date?
A longer or shorter menstrual cycle can shift likely ovulation timing. Adjusting the cycle length helps the calculator estimate conception more realistically when LMP is used.
3. Can this calculator confirm the exact delivery day?
No. It estimates a probable due date. Birth can happen before or after that date, and your care team may revise timing using scan findings or medical needs.
4. Does IVF dating work differently?
Yes. IVF dating uses the transfer date and embryo age, so conception timing is more precisely estimated than many non-IVF pregnancy calculations.
5. What does gestational age mean?
Gestational age counts from the estimated LMP, not actual fertilization. That is why pregnancy is commonly dated about two weeks earlier than conception.
6. Why are milestone ranges shown instead of single dates?
Many pregnancy events and tests are scheduled within recommended windows. Ranges are more practical because clinic timing, growth, and provider preferences can differ.
7. Can I use this after my due date passes?
Yes. The tool will still show your timeline and indicate how many days you are past the estimated due date for ongoing tracking.
8. Is this calculator medical advice?
No. It is an educational planning tool. Always follow medical advice from your doctor, midwife, fertility specialist, or maternity clinic for real decisions.