Pregnancy due date calculator
Enter the first day of your last menstrual period (LMP) to estimate a due date 280 days later. This conventional estimate can differ from the date established by your prenatal care team.
How the estimate works
The calculator adds 280 days (40 weeks) to the first day of the LMP. This is a conventional estimate, not a prediction of the day of birth. Cycle length and ovulation vary; if the LMP is unknown, cycles are irregular, or conception followed fertility treatment, a clinician may use other information to date the pregnancy.
Prenatal care in Brazil
Brazil’s Ministry of Health recommends starting prenatal care as soon as pregnancy is suspected or confirmed, preferably by 12 weeks. Consult the prenatal team to establish and document your individual due date. Outside Brazil, follow your local health service.
Frequently asked questions
Does the calculator tell me when I conceived?
No. It estimates a due date from the LMP and cannot determine the date of conception.
My clinician gave me a different due date. Which should I use?
Discuss the difference with your prenatal team. LMP history and ultrasound findings may be considered together; the calculator cannot set or revise a clinical due date.
Does the due date mean the baby will arrive that day?
No. It is an estimate, not a scheduled or guaranteed birth date.
Does this replace prenatal care?
No. It does not confirm pregnancy or assess the health of a pregnant person or fetus. Keep prenatal appointments and seek care for concerns.