BabySize

More than numbers

Turn your ultrasound measurements into a life-size outline of your baby.

◌ Based on your ultrasound measurements◌ Free to use · No sign-up needed

Your ultrasound measurements, pictured

Use four measurements to picture your baby's size

Screen not calibrated
Sample preview · Enter your measurements to begin Sample baby size illustration, blurred until you enter measurements
Start with your scan

Enter your ultrasound measurements to picture your baby's size.

Edit measurements

Your ultrasound measurements

Use millimeters (mm). Decimals allowed.

weeks

14–40 weeks

mm

mm

mm

mm

Use a whole number from 14 to 40 weeks and measurements in millimeters. Head proportions stay fixed; BPD is recorded only.

Calibrate your screen

Measure the line below with a ruler from the center of one end mark to the other, then enter its length in millimeters. This adjusts the illustration and scale bar together.

Reference line
mm

After calibration, select “Actual size (100%).” At 200%, 1 cm appears as about 2 cm on screen. Recalibrate if you change screens or browser zoom.

Your ultrasound, explained

Four measurements. A clearer picture.

Find BPD, HC, FL and AC on your ultrasound report to get started.

This illustration helps you picture size. It doesn't show your baby's actual appearance or assess development.

BPD

Biparietal diameter

The width of your baby's head, measured between the parietal bones on either side.

Across the head; HC measures around it.

Where it's measured
HC

Head circumference

The distance around the head on a standard ultrasound cross-section.

The circumference, rather than the width.

Where it's measured
FL

Femur length

The length of the shaft of the femur, or thigh bone.

This measures the bone shaft, rather than the whole leg.

Where it's measured
AC

Abdominal circumference

The distance around the abdomen on a standard ultrasound cross-section.

The circumference, rather than the width.

Where it's measured

Use millimeters (mm). Check your report before entering the measurements.

Source: ISUOG fetal ultrasound measurement guidelines
Understanding BPD, HC, FL and AC ↗

Get the scale right

Bring the on-screen size closer to life

Every screen displays images a little differently. Calibrate with a ruler to bring the illustration's scale closer to real-world size on this device.

  1. Calibration diagram

    Open calibration

    Create your illustration, then select “Calibrate screen.”

  2. Calibration diagram

    Measure the line

    Use a ruler to measure the reference line on screen. Enter its length in millimeters.

  3. Calibration diagram

    View at 100%

    Select “Apply calibration,” then “Actual size (100%).” Check the scale bar with your ruler.

  • “Fit to screen” shows the whole illustration at a convenient viewing size.
  • Recalibrate if you change screens or browser zoom.
  • Calibration adjusts the display scale. The outline is still an illustration of size, not actual appearance or posture.

More on screen calibration ↗

A keepsake to hold

Turn the outline into a paper keepsake

  1. Black-and-white baby outline on a computer screen

    Prepare the outline

    Turn off measurement labels, choose “Outline only,” and use the calibrated “Actual size (100%)” view.

  2. A hand lightly tracing the baby's outline onto paper held against a computer screen

    Trace it onto paper

    Place a sheet of paper gently against the screen and trace lightly in pencil.

  3. A white paper cut-out of a baby's outline resting on a pregnant belly

    Hold it against your bump

    Cut along the outline and rest it gently against your bump for a sense of your baby's size.

Add the date, your week of pregnancy and a note to your baby on the back—a small reminder of this moment.

Keep the calibrated 100% view while tracing. The outline is a size guide.

Saving images and making keepsakes ↗

Checking sign-in status…

A few things to know

Common questions

What if my report is missing a measurement?

You'll need all four measurements and your week of pregnancy. Check your report for anything missing; don't guess or substitute another value.

Why hasn't my illustration updated?

After editing the measurements, select “Create illustration” again. The image changes once the new illustration is ready.

Why doesn't BPD change the head shape?

BPD is saved and shown as a label, but it doesn't change the drawing. Head circumference sets the head's overall size while the reference proportions stay the same.

Why does the size look different on another device?

Screen settings and zoom affect the displayed size. Calibrate each device you use and view at 100% to check physical length.

Will my download display or print at actual size?

Not automatically. Screen calibration doesn't carry over to the download. Display and print settings affect its size, so check the image's scale bar with a ruler.

Should I download the image or save the measurements?

Download to keep the image on your device. Save measurements to keep the week, values and record name in your account so you can reopen them later. You can do both.

Can this tell me if my baby is developing normally?

No. BabySize helps you picture size and make a keepsake; it doesn't assess development. Ask your prenatal care provider to explain your ultrasound results in the context of your care.

A little more guidance

Understand the measurements, get the scale right and keep a memento.

Keep your image and measurements

Download your illustration, save measurements to revisit later or make a paper keepsake.

October 24, 2026BabySize

How to calibrate your screen

Check your illustration at 100% with a ruler, with tips for changing screens, downloading and printing.

October 24, 2026BabySize

Understanding BPD, HC, FL and AC

A visual guide to the four ultrasound measurements and how BabySize uses them.

October 24, 2026BabySize
View all guides