Early Ultrasound Visibility and Best Scan Date Calculator

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Estimate the chance of seeing a gestational sac or yolk sac on transvaginal ultrasound, and a possible scan date based on your hCG trend.

The 48-hour starting value is editable. Actual hCG changes vary.

This calculator is for transvaginal ultrasound in an early viable singleton pregnancy. hCG alone cannot diagnose viability or an ectopic pregnancy.
Peer-Reviewed Science
Updated Dec 2025
See Methodology
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Methodology

Published logistic equations estimate gestational-sac and yolk-sac visibility from hCG in viable singleton pregnancies. The date projection applies the editable hCG doubling time to the selected visibility target.