Due Date from Ultrasound (CRL)
Gestational age and EDD from crown-rump length using the Robinson–Fleming dating curve.
Between 7 and 13 weeks, embryos grow so uniformly that CRL dates a pregnancy to ±5 days — the most accurate window there is, which is why guidelines anchor dating to this scan. Your radiologist's machine applies this same curve (or a near-identical one); always defer to the formal report.
Formula
For general information only. Pregnancy and infant care decisions must be guided by your treating clinician or midwife — always defer to their assessment.
Gestational age and EDD from crown-rump length using the Robinson–Fleming dating curve. The Due Date from Ultrasound (CRL) is a free, private crl calculator tool — every result computes instantly in your browser with no sign-up and no data upload.
About Due Date from Ultrasound (CRL)
Between 7 and 13 weeks, embryos grow so uniformly that CRL dates a pregnancy to ±5 days — the most accurate window there is, which is why guidelines anchor dating to this scan. It applies GA(days) = 8.052 × √CRL(mm) + 23.73 (Robinson–Fleming). Use the Due Date from Ultrasound (CRL) to get an instant, clearly-explained result with the working shown step by step — free, private and with the source method cited.
How to use Due Date from Ultrasound (CRL)
- 1Enter your details in the Due Date from Ultrasound (CRL) input fields above.
- 2The result updates instantly with the working and reference bands shown.
- 3Adjust any value to explore how it changes the outcome — it's free and unlimited.
Why use Due Date from Ultrasound (CRL)?
- ✓Instant crl calculator result that recomputes as you type — no waiting, no page reloads
- ✓100% client-side: your health data never leaves your browser
- ✓Shows the actual formula and your numbers substituted in, so you can see exactly how the result is reached
- ✓Based on published, citable sources (Robinson HP & Fleming JEE, BJOG 1975 — CRL dating curve)
- ✓Free forever with no sign-up, account or app install
Frequently asked questions
How does the Due Date from Ultrasound (CRL) work?+
Between 7 and 13 weeks, embryos grow so uniformly that CRL dates a pregnancy to ±5 days — the most accurate window there is, which is why guidelines anchor dating to this scan. The calculation uses the formula: GA(days) = 8.052 × √CRL(mm) + 23.73 (Robinson–Fleming). Everything runs instantly in your browser as you type — your inputs are never uploaded.
Is the Due Date from Ultrasound (CRL) accurate, and what is it based on?+
The method is traceable to authoritative sources, including Robinson HP & Fleming JEE, BJOG 1975 — CRL dating curve; NICE NG201 — antenatal care (dating scan). Results are estimates — individual variation always applies, so treat the output as a well-grounded starting point.
Is the Due Date from Ultrasound (CRL) free and private?+
Yes. It's completely free with no sign-up, and all computation happens locally in your browser, so none of your health data ever leaves your device.
Can I use this for medical decisions?+
This tool is informational only. Always defer to your treating clinician or midwife for pregnancy and infant care decisions.
What can I use the Due Date from Ultrasound (CRL) for?+
It's commonly used for crl calculator, ultrasound due date, crown rump length. Gestational age and EDD from crown-rump length using the Robinson–Fleming dating curve.
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