Estimated Date of Birth Calculator
1Method of conception
280 days from LMP, adjusted by one day for each day the cycle differs from 28. The adjustment assumes the variation sits in the follicular phase.
Estimated date of birth is 266 days from this date.
Transfer date plus 266 days, less the age of the embryo at transfer. Applies to both fresh and frozen cycles. IVF dating stands; ultrasound does not override it.
2Ultrasound (optional)
Robinson–Fleming dating. Applies between 10 and 84 mm.
Use the gestation stated on the report.
3Which estimated date of birth to use
Enter a date to begin.
weeks
Defaults to today. Change it to date a retrospective note or to look ahead.
- Estimated date of birth in use
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- Trimester
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- Days to estimated date of birth
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- Reaches 37 weeks
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- Reaches 42 weeks
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- CRL dating window (8+0 to 13+6)
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Key dates across the pregnancy
Schedule prompts only. Adjust to your own care pathway.
This is a calculation aid only. Dating decisions, discrepancy thresholds and escalation follow your clinical judgement. All dates should be reviewed for accuracy.