Cephalic Index
Maximum head width as a percentage of maximum length. The result updates as you type.
Method
Cephalic index = width ÷ length × 100
Normal values vary with age, sex, and population, and published cutoffs differ. The bands here follow those commonly used in the positional brachycephaly literature. Age- and sex-specific normative percentiles for the first year of life have been published and are preferable for borderline values.
A low index suggests a long, narrow head, as seen in sagittal synostosis (scaphocephaly) and in positional dolichocephaly of preterm infants. A high index suggests brachycephaly, which may be positional or reflect bicoronal synostosis. The index alone cannot distinguish these causes.
Severity bands as used in J Clin Med. 2020;9(4):1027 (PMC7231243). Normative data: Wilbrand JF, et al. Clinical classification of infant nonsynostotic cranial deformity. J Pediatr. 2012;161(6). Find on PubMed.
- < 75Dolichocephalic rangelong, narrow
- 75 to 90Commonly used reference range
- > 90 to 93Mild brachycephaly
- > 93 to 97Moderate brachycephaly
- > 97Severe brachycephaly