EDD means estimated due date. It is the date used for planning prenatal care, but it is not a promise that labor will start on that day.

Why can my doctor's due date differ?

Your clinician can combine LMP, cycle history, early ultrasound, IVF records and clinical details. That medical dating should take priority over an online estimate.

Can I plan a birth month with the reverse mode?

Reverse mode only gives a rough conception-period estimate. It cannot control the actual day of birth.

Due Date Calculator

Estimate a pregnancy due date from last menstrual period, conception date, IVF transfer or ultrasound dating, with term windows and reverse planning.

Due date details

Medical estimate: Only your pregnancy care provider can confirm or revise your official EDD. Use this calculator for planning, not for diagnosis, induction timing or medical decisions.

Mode

Calculate from pregnancy dates

Plan from a target due date

Calculation method

Last period

Conception date

IVF transfer

Ultrasound dating

First day of last menstrual period

Cycle length, days

Pregnancy history

Estimated due date methods

Due date calculators in US search results usually support LMP first, then conception, IVF and ultrasound-based dating. The result is an estimate, not a guaranteed birth date.

EDD_{L M P} = LMP + 280 days

Naegele-style due date estimate from last menstrual period.

EDD_{co n ce pt i o n} = conception + 266 days

Due date estimate when conception or ovulation is known.

EDD_{I V F 5} = transfer + 261 days

Common 5-day embryo transfer estimate.

Term windows

Category	Gestational age
Early term	37 weeks 0 days through 38 weeks 6 days
Full term	39 weeks 0 days through 40 weeks 6 days
Late term	41 weeks 0 days through 41 weeks 6 days
Postterm	42 weeks 0 days and beyond

Care decisions need clinical review

Do not use an online calculator to choose induction timing, medication or monitoring. Follow the due date and plan set by your pregnancy care provider.

Frequently Asked Questions

Sources and References

Calculations are based on the listed reference sources. Links open in a new tab.

Updated: June 2, 2026

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