- Estimated due date
- 2027-04-07
- Gestational age on selected date
- 14 weeks, 2 days
- Estimated conception
- 2026-07-15
How it works
Embryo age changes the remaining interval
For the same transfer date, a five-day embryo gives a due date two days earlier than a three-day embryo. The embryo has already developed longer; enter its age at transfer, not today’s age.
Understanding an estimated due date
An estimated due date depends on the dating method and the accuracy of the information entered. Choose the menstrual, conception, IVF, or ultrasound mode that matches the source of your dates. A due date is a reference point for a pregnancy timeline rather than a prediction of the exact day of birth. Clinical dating may differ when additional information is available.
Last menstrual period: formula and assumptions
Estimated due date = LMP + 280 days + (cycle length−28).
Gestational age is conventionally counted from the last menstrual period. Ultrasound and clinical assessment can revise the estimate.
Conception date: formula and assumptions
Estimated due date = conception + 266 days.
A conception date is generally an estimate unless linked to assisted reproduction.
IVF transfer: formula and assumptions
Estimated due date = transfer date + 266 − embryo age days.
Confirm assisted-reproduction dates with your treating clinic.
Ultrasound dating: formula and assumptions
Estimated due date = scan date + (280−gestational days).
Use the gestational age supplied in the clinical ultrasound report.
Worked example
Using the Last menstrual period example:
- First day of last menstrual period
- 2026-07-01
- Typical cycle length (days)
- 28
- Calculate gestational age on
- 2026-10-09
Estimated due date = LMP + 280 days + (cycle length−28).
Example result
Estimated due date: 2027-04-07
Gestational age on selected date: 14 weeks, 2 days
Estimated conception: 2026-07-15
These are illustrative inputs. Change the values to explore a different scenario.
What to keep in mind
Dates are estimates, not a prediction of the exact day of delivery.
Formula references
References explain the underlying methods; they do not imply endorsement or individual professional review of Finflo.
Common questions
How does embryo age affect IVF due-date calculation?
The model adds 266 days to the transfer date, then subtracts the embryo's age in days at transfer.
What should I enter for ultrasound dating?
Use the scan date and gestational age reported by the clinical ultrasound assessment, rather than estimating fetal age yourself.
Prepared by Finflo. See our methodology and editorial policy. Read the relevant professional-advice limitations.