Pregnancy Due Date Calculator: Weeks, Trimester & Progress

Free pregnancy due date calculator

A pregnancy due date is an estimate of when a baby may arrive. The most common method counts 280 days from the first day of the last menstrual period. If conception date is known, a common estimate is 266 days from conception. IVF pregnancies may be estimated from transfer date and embryo age.

This calculator also estimates gestational age, trimester, days remaining, and pregnancy progress. It is designed for education and planning, not medical diagnosis.

How due date estimates work

Pregnancy dating is based on assumptions. Ovulation timing can vary, cycle length can vary, and not every pregnancy follows the same timeline. A healthcare professional may use ultrasound and medical history to refine the estimate.

LMPDue date = first day of last period + 280 days

ConceptionDue date = conception date + 266 days

IVFDue date = transfer date + 266 days − embryo age

How to use your due date estimate

Use this estimate for general planning, then confirm pregnancy dating with prenatal care. The due date is not a deadline. Many healthy pregnancies deliver before or after the estimated date.

Example

If the first day of the last menstrual period was January 1 and cycle length is 28 days, a standard estimate adds 280 days. If the cycle is longer or shorter, the calculator adjusts the estimate slightly because ovulation may have occurred later or earlier.

Frequently asked questions

How is pregnancy due date calculated?

A common estimate is 280 days from the first day of the last menstrual period, or 266 days from estimated conception.

Is the due date exact?

No. A due date is an estimate, not a guaranteed delivery day.

Can an ultrasound change the due date?

Yes. A healthcare professional may adjust dating based on early ultrasound findings and medical context.

What are the trimesters?

A simple breakdown is first trimester through week 13, second trimester from week 14 through week 27, and third trimester from week 28 to birth.

Can IVF transfer date be used?

Yes. IVF dating can estimate due date from transfer date and embryo age, commonly day 3 or day 5.