Ultrasound Due Date Calculator
Estimate a due date from the gestational age recorded on an ultrasound report.
Your details
Enter only the information needed for this estimate.
Complete the fields and select “Estimate from an ultrasound” to see your estimate.
Due date estimated from the scan age
This calculation adds the remaining time in a 40-week pregnancy to the gestational age entered from the report.
A scan report may show more than one age or date. Use the due date formally assigned by your care team.
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What to enter
Use the gestational age documented for dating on the ultrasound report, including both weeks and extra days. Do not substitute a fetal size percentile, an anatomy measurement, or an age copied from a pregnancy app.
If the report lists several measurements or dates, ask your care team which one is used for official dating.
How ultrasound fits into pregnancy dating
Ultrasound measurements can help establish or confirm gestational age. Earlier scans generally provide more useful dating information than later size measurements, because normal differences in fetal size increase as pregnancy progresses.
Clinicians compare ultrasound findings with menstrual dates and any assisted reproduction timing. A calculator cannot apply all of the criteria used to decide whether an established due date should change.
Limits of this estimate
- The result is only as reliable as the gestational age copied from the report.
- Later-pregnancy fetal size should not be treated as a precise conception date.
- This tool cannot choose between conflicting dates or decide whether clinical redating criteria are met.
Common questions
How should I use this estimate?
Use it as a planning starting point, then compare it with your own experience and any guidance from a qualified health professional.
Is this medical advice?
This calculator provides a general educational estimate. It does not interpret an ultrasound, assess fetal growth, or replace the due date documented by a qualified maternity professional.
What happens to what I enter?
The calculator uses the values in your current browser session to produce the result. It does not save them in browser storage.