Free Tool
Assess your baby's head asymmetry with two measurements
CVAI (Cranial Vault Asymmetry Index) is the most widely used numerical measure of flattening in an infant's head. Enter the two diagonals and see the result and what it means.
Enter the measurements
Optional: cephalic index
The cephalic index is the width-to-length ratio of the head. Roughly 76–81% is considered typical; higher values can indicate brachycephaly (flattening at the back), lower values dolichocephaly.
How to measure
- 1With your baby calm, position yourself so you look down at the top of the head.
- 2Run a flexible tape diagonally from just above one eyebrow to behind the opposite ear (Diagonal A).
- 3Repeat the same measurement in the other direction (Diagonal B).
- 4Enter both values in millimetres.
Result
Enter both diagonals to see the result.
This is not a diagnostic tool
This calculator is for information only. Measurements taken at home with a tape measure are not of clinical accuracy and cannot be used to make a diagnosis on their own. Decisions about head shape, development or treatment can only be made by the doctor or orthotist who examines your baby.
Why timing matters
The most effective period for head shape treatment is roughly between the 4th and 8th month, when the skull grows fastest and is most responsive to reshaping. If you have a concern, an early assessment keeps more options open.
Automate this measurement in your clinic
Clonify computes CVAI and the cephalic index automatically from a 3D scan, paints the asymmetry onto the surface as a heat map, and produces the clinician-approved helmet design in the same flow.
Are you a family? Ask us for the nearest clinic using Clonify. Get in touch