Read more: FAQs & context
Charts vary
Hospitals may use Intergrowth, Robinson, or local polynomials. Your printed report is authoritative.
Ultrasound dating
Enter CRL in millimetres and the date of the scan to estimate GA and EDD (first-trimester style).
Purpose, how to use it, and benefits — the interactive tool is in the card above whenever you want to jump back.
Crown–rump length (CRL) in millimetres on a scan date can estimate gestational age in the first trimester. We interpolate a standard mm-to-days table to suggest an implied LMP and EDD.
Enter CRL in mm and the scan date, then Estimate due date. Copy the summary if you want to discuss discrepancies with your sonographer.
You can see how ultrasound dating might shift your “paper” LMP due date, which explains why two apps show different weeks.
Hospitals may use Intergrowth, Robinson, or local polynomials. Your printed report is authoritative.