Health
Pregnancy Calculator
Estimate due date, pregnancy week, conception dating and an IVF timeline.
Date a pregnancy
Choose the most reliable known date basis. All results are calendar estimates.
With irregular cycles, LMP, ovulation, conception and fertile-window estimates can be substantially less accurate.
Result
Estimated dating
June 28, 2027
The calculated due date is an estimate, not a guaranteed birth date.
The date is within the calculated pregnancy period.
Dating method
Cycle length
Actual ovulation can differ. This estimate is not suitable for reliable contraception.
Pregnancy timeline
Dating milestones
How dating works
Medical gestational counting usually starts on the first day of the LMP. A 28-day cycle uses 280 days; a different cycle length adjusts that estimate.
Estimated conception is conventionally 266 days before the EDD. The first trimester ends at 13+6, the second at 27+6 and the third starts at 28+0.
IVF dating uses transfer date and embryo age. Early ultrasound can confirm or revise LMP dating more accurately; this calculator does not interpret ultrasound measurements.
The calculated due date is an estimate, not a guaranteed birth date.
Results do not replace medical dating or advice. Use a date assigned by a clinician or early ultrasound as the primary reference.
Sources and data status: ACOG, NHS, Assurance Maladie and WHO; verified 9 August 2026.
- American College of Obstetricians and Gynecologists (ACOG): Methods for Estimating the Due Date
- American College of Obstetricians and Gynecologists (ACOG): How Your Fetus Grows During Pregnancy
- American College of Obstetricians and Gynecologists (ACOG): Fertility Awareness-Based Methods of Family Planning
- NHS: Pregnancy due date calculator
- Assurance Maladie (ameli.fr): Grossesse : premiers signes et déroulement
- World Health Organization: Imaging ultrasound before 24 weeks of pregnancy: 2022 update
Frequently asked questions
What does 12+3 mean?
Twelve full weeks and three days have elapsed since the gestational reference.
How is the due date calculated?
From LMP, a known EDD, assumed conception, or embryo transfer depending on the selected mode.
When do trimesters begin?
The second begins at 14+0 and the third at 28+0.
Can the fertile window prevent pregnancy?
No. Ovulation and fertile days can vary.
How is IVF dated?
A day-5 transfer adds 261 days and a day-3 transfer adds 263 days.
Is ultrasound more accurate?
An early ultrasound can estimate gestational age more accurately or confirm LMP dating.