How to use this calculator
Select a dating method and enter its calendar information. The main answer is the expected due date, followed by gestational weeks and days and a table of pregnancy milestones. Day-5 IVF transfers add 261 days, day-3 transfers add 263 days, and day-6 transfers add 260 days. The milestones are dating landmarks, not a clinical appointment schedule.
- Enter dating information, calculate pregnancy age on, first day of last menstrual period and review the remaining options.
- Select Calculate or change a value to update the result. Read the result label and units before copying.
- Use Reset to restore the worked starting values.
Formula and method
A natural conception date cannot be identified exactly by this tool and must not be used to establish paternity. Obstetric age starts about two weeks before fertilization in a typical cycle. Early ultrasound and medically established dating may be more reliable. Irregular cycles weaken LMP estimates. Due dates are estimates, not guarantees of delivery on one day.
Worked example
A day-5 embryo transferred on 20 September 2026 gives an estimated due date of 8 June 2027 (261 days later). A scan on 27 October 2026 reporting 8 weeks and 0 days gives the same due date.
Questions about due date calculator
When is my baby due?
A 28-day-cycle estimate adds 280 days to the first day of the last period. A day-5 IVF transfer adds 261 days instead. Ultrasound dating uses the scan date and reported gestational age. These methods estimate a due date rather than the exact delivery day.
What assumptions should I check?
A natural conception date cannot be identified exactly by this tool and must not be used to establish paternity. Obstetric age starts about two weeks before fertilization in a typical cycle. Early ultrasound and medically established dating may be more reliable. Irregular cycles weaken LMP estimates. Due dates are estimates, not guarantees of delivery on one day.
Are my inputs saved?
Calculations run in your browser. We store only tool IDs for favorites and recent tools. Sharing inputs in links is disabled for this category.
Health tools provide general estimates, not diagnoses or personal medical advice. BMI offers a labeled CDC child/teen reference; adult screening bands must not be applied to children. Discuss health and exercise decisions with a qualified professional. Read the tool-specific sources below for background on the method.