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Try an Example
Pick a scenario to see how the calculator works, then adjust the values
Due Date from LMP
Calculate the due date using the first day of the last menstrual period (10 weeks ago).
Key values: LMP method · 28-day cycle · Singleton
First Trimester Check
A pregnancy at approximately 8 weeks from conception date.
Key values: Conception method · 8 weeks ago · First trimester
Ultrasound Dating
Calculate timeline from an ultrasound performed at 12 weeks, 3 days.
Key values: Ultrasound method · 12w 3d at scan · 4 weeks ago
IVF Transfer Timeline
Estimate due date from a day-5 embryo transfer completed 14 days ago.
Key values: IVF method · Day-5 transfer · High confidence dating
This calculator is also known as Due Date Calculator.
Read the complete guideWhat a Due Date Actually Means
A due date is a planning estimate, not a guarantee. Clinicians use it to time prenatal screening, growth checks, and decisions later in pregnancy. The calculation framework is based on gestational age conventions used in obstetric care, which count from the first day of the last menstrual period rather than from fertilization.
Examples
LMP-Based Example
Last menstrual period started on January 1 with a typical 28-day cycle.
The estimated due date is calculated by adding 280 days to the LMP date.
Key takeaway: LMP dating is common, but ultrasound can refine dating if cycle timing is uncertain.
After You Calculate Your Due Date
Use this date to schedule prenatal appointments, screening windows, and practical planning for maternity leave and delivery preparation.
- Book prenatal appointments according to gestational age milestones
- Review screening timelines with your healthcare provider
Frequently Asked Questions about Due Date Calculator
How accurate is a due date calculator?
A due date is an estimate. Most babies are born within a window around the estimated date rather than on the exact day.
Which due date method is usually most accurate?
Early ultrasound dating and IVF transfer dating are typically the most precise, followed by conception date and LMP-based estimation.
Specialized Calculators
Choose from 4 specialized versions of this calculator, each optimized for specific use cases and calculation methods.
Method
3 CalculatorsAlternative methods and approaches
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