Due Date Calculator
Estimate an expected due date from LMP, conception date, or cycle length.
This page is an editable estimator with realistic defaults so you can model your own situation in minutes.
Due date is estimated as LMP + 280 days adjusted for cycle length, or conception date + 266 days.
Treat the result as a planning estimate and verify important numbers with the relevant official source before acting.
| Cycle length | 28 days | |
|---|---|---|
| Method | lmp |
Assumptions
- ACOG describes estimated due date as a best obstetric estimate, not a guarantee.
- Only a pregnancy care professional can confirm dating for clinical decisions.
How this calculator works
Formula used
Due date is estimated as LMP + 280 days adjusted for cycle length, or conception date + 266 days.
Example calculation
Plug in your own numbers and the result updates instantly. Due date is estimated as LMP + 280 days adjusted for cycle length, or conception date + 266 days.
Due Date Calculator FAQ
Is this due date calculator medical advice?
No. It is an educational estimate only and does not replace an OB-GYN, midwife, fertility specialist, pediatric clinician, or emergency care.
Why might my actual dates or recommendations differ?
Cycle length, ovulation timing, ultrasound dating, implantation timing, multiples, medical history, and clinician judgment can change pregnancy and fertility estimates.
Should I confirm results with a clinician?
Yes. Confirm pregnancy dating, weight gain, cycle concerns, fertility timing, or health decisions with a qualified healthcare professional.