Evidence-Based Ultrasound Dating for Parents & Clinicians
CRL Age Calculator (crlagecalculator.com) is an independent, free, evidence-based sonographic reference designed to clarify first-trimester ultrasound reports and dating scans.
Why We Built This Tool
Ultrasound scan reports often contain medical terminology like "CRL 24.0mm = 9w1d ± 4d" without intuitive context. Expectant parents and healthcare students frequently struggle to interpret how a tiny millimetric measurement directly establishes an Estimated Due Date (EDD) or reconciles against Last Menstrual Period (LMP) timing.
Our goal is to demystify obstetric biometric dating using verified medical literature, peer-reviewed formulas, and intuitive visualization.
Scientific Standards & Clinical Citations
Robinson & Fleming (1975)
The gold standard regression adopted by the British Medical Ultrasound Society (BMUS), NICE, and The Fetal Medicine Foundation (FMF).
Hadlock et al. (1992)
Radiology benchmark correlation study providing high-resolution sonographic validation across 5 to 18 gestational weeks.
ACOG Committee Opinion 700
American College of Obstetricians and Gynecologists consensus on resolving dating discordance between ultrasound biometry and menstrual history.
Zero Data Storage
Your health data is completely private. All calculations run strictly client-side inside your browser without transmitting your ultrasound measurements to servers.
Questions or Clinical Inquiries?
We welcome feedback from obstetricians, radiologists, ultrasound sonographers, and midwives to ensure our mathematical modeling reflects best clinical practice.
Contact Clinical Editorial Team