billycalc

Head Circumference

Head Circumference: calculated with the published clinical method, with result interpretation. A reference tool that does not replace a doctor's advice.

ℹ Reference calculation based on the published method. It does not replace a clinical examination or a doctor's decision.

Head Circumference

Age (completed months)mo
Girl (1 = yes)
Head circumferencecm
Head circumference-for-age percentile (WHO)
50
WHO growth standards, 0–5 yearsAge is rounded to whole monthsReference calculation; the decision rests with the physicianHead Circumference: calculated with the published clinical method, with result interpretation. A reference tool that does not replace a doctor's advice.
z-score (SDS)
0.00
WHO median for age
42.2cm
WHO interpretation
Within normal limits

More about: Head Circumference

What it calculates

The “Head Circumference” calculator computes Head circumference-for-age percentile (WHO) from 3 parameters: age (completed months) (months), girl (1 = yes), head circumference (cm).

Used by professionals and patients to assess health metrics, dosages, and risks.

Example calculation

With parameters Age (completed months) = 6 months, Girl (1 = yes) = 1, Head circumference = 42.2 cm the result is 50 (WHO growth standards, 0–5 years).

How to use

  1. Enter age (completed months), girl (1 = yes) and head circumference — each field above is adjustable with a slider.
  2. Head circumference-for-age percentile (WHO) is calculated automatically as you type.
  3. Check the worked example below to see the formula applied to real numbers.
  4. Copy the result or bookmark this calculator.

Related calculators

FAQ

How is BMI calculated?
BMI = weight (kg) / height (m)². Example: 70 kg / (1.75 m)² = 22.9. The WHO normal range is 18.5–24.9; below that is underweight, 25–29.9 is overweight, and 30+ is obese.
Is BMI accurate for everyone?
No. BMI does not distinguish muscle from fat, so athletes may show a high BMI with low body fat. It is also less reliable for teenagers, pregnant people, older adults, and very tall or short individuals.
What are the BMI categories?
Underweight: below 18.5. Normal: 18.5–24.9. Overweight: 25–29.9. Obese class I: 30–34.9; class II: 35–39.9; class III: 40+.
What is a better measure than BMI?
Body fat percentage, waist-to-height ratio (aim for under 0.5), and waist circumference give a clearer picture of health than BMI alone.

More calculators in this category

Explore related free tools

Marshall CTRotterdam CTIMPACT TBICRASH TBIPERC RuleYEARS AlgorithmD-dimer Age-AdjustedPulmonary Embolism IndexDabigatran ReversalHeparin DosingWarfarin DosingDOAC Renal Dosing