About BabySize

Ultrasound reports give you numbers. BabySize helps you picture what they mean in terms of size—and make a keepsake of this stage of pregnancy. On the home page, enter your week of pregnancy and four measurements to create an illustration. You can then calibrate the screen, download the image or trace the outline onto paper.

Who writes our guides?

The BabySize team maintains the content published under our name. Our guides explain the four ultrasound measurements and how to use the tool. Each article shows when it was published and last updated; we revise instructions as features change.

Our guides help you find the right measurements and use BabySize. Your prenatal care provider is the right person to explain your test results and answer questions about your health.

Our sources

The names and measurement locations for biparietal diameter, head circumference, femur length and abdominal circumference draw on ISUOG's guidelines on fetal biometry and growth assessment and guidelines on the routine mid-trimester fetal ultrasound scan (2022 update). The relevant pages list their sources so you can read further.

The measurement location diagrams are drawn by BabySize to help you identify items on your report; they are not intended to guide ultrasound procedures. The how-to guides are written based on the site's current interface and features. Scenario images such as the pregnancy belly cutout are used to demonstrate keepsake ideas; they are not evidence of a real individual or a medical examination.

How the illustration works

The tool starts from a reference outline and adjusts the corresponding parts using the measurements from your report. Currently, biparietal diameter is recorded and displayed but does not adjust the head shape on its own; the head keeps the proportions of the reference image, and its overall size follows head circumference. The illustration isn't a three-dimensional reconstruction of your baby and can't show their actual appearance or posture.

Screen calibration matches the display length on your current device. To check whether it is close to actual size, compare it against the scale bar in the image using a physical ruler. For more, see the four measurement diagrams and the calibration guide.

What BabySize is for

Use BabySize to picture measurements, share a moment with family or make a keepsake. It doesn't assess development, provide medical reference ranges or estimate how far along a pregnancy is.

If you find an error in an explanation, link or how-to instruction, please let us know through the contact page. For questions about accounts and data storage, please see the privacy policy.