Pregnancy Tools

Due Date Calculator

Estimate your pregnancy due date (EDD) using LMP, conception date, IVF transfer date, or a known due date—plus gestational age, trimester, and milestones.

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Dating method

A due date is an estimate, not an exact delivery date. Early ultrasound is often the most accurate way to confirm dating.

Inputs

Enter the dates you know; we calculate EDD and related dates.

First day of last period (LMP) i

Average cycle length (days) i

Typical range: 21–35 days.

Note: Irregular cycles can shift ovulation. Ultrasound may revise dating.

Current date

Used for gestational age and “days remaining”.

Show milestone timeline

Tip: Most births don’t happen on the exact due date.

Results

These are estimates. Ultrasound may confirm or revise dating.

Estimated due date (EDD)

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Enter your details and calculate to see an estimate.

Estimated conception

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≈ Due date − 266 days

Estimated LMP

—

Pregnancy dating baseline

Days remaining

—

From current date to due date

Current date

—

Used for gestational age

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How a due date is calculated

This due date calculator uses common clinical pregnancy dating rules. Most pregnancies are dated from the first day of the last menstrual period (LMP), and the estimated due date (EDD) is calculated as 280 days (40 weeks) from that date.

If a conception date is known, the due date is often estimated as 266 days (38 weeks) after conception. For IVF pregnancies, dating can be based on embryo transfer date and embryo age at transfer.

Early ultrasound is often the most accurate way to confirm or revise a due date, especially in the first trimester. Remember: a due date is an estimate and many births happen before or after it.

LMP vs conception vs IVF dating

LMP dating counts from the last period. Conception dating starts closer to fertilization timing. IVF dating uses transfer date plus embryo age at transfer to estimate gestational timing.

Why ultrasound may change due date

Ovulation timing varies, especially with irregular cycles. An early ultrasound can provide a measurement-based estimate and may revise the due date if it differs from period-based dating.

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FAQ

Questions people ask

How is a due date calculated?

A common method is 280 days (40 weeks) from the first day of the last period (LMP). Other methods use conception date, IVF transfer date, or ultrasound dating.

Is pregnancy counted from the last period or conception?

Clinically, pregnancy weeks are usually counted from LMP, which is typically about 2 weeks before conception in a 28-day cycle.

Can ultrasound change my due date?

Yes. Early ultrasound is often the most accurate way to confirm or revise dating, especially if cycles are irregular.

How do IVF due dates work?

IVF dating can use transfer date and embryo age (for example day 3 or day 5 transfer) to estimate the due date.

Is this due date calculator accurate?

It provides an estimate. Individual medical dating can differ and may be confirmed or revised by ultrasound.

Disclaimer

This calculator is for informational purposes only and does not provide medical advice. For personalized guidance, consult a qualified healthcare professional.