Girls Head chart in inches for Toddlers 20 month old

Head circumference chart for 20-Month-Old girls

Head circumference at 20-Month-Old: what the growth charts show for toddler girls.

Head circumference percentiles for 20-Month-Old girls

Using CDC reference standards, the head circumference percentiles for toddler girls at 20-Month-Old are:

• 5th percentile: 17.5 in

• 25th percentile: 18.1 in

• 50th percentile (median): 18.4 in

• 75th percentile: 18.8 in

• 95th percentile: 19.3 in

The percentile values on this page are displayed in inches.

Growth percentiles place your child's measurement on a scale from 1 to 99 relative to toddler girls. The 50th percentile represents the middle of the typical range.

What to expect at 20-Month-Old

Head circumference growth slows markedly in the second year compared to infancy, though brain development continues rapidly. By 12 months, the brain is approximately 60% of its adult size; by 24 months it is closer to 80%. The anterior fontanelle typically closes between 12 and 18 months, and head circumference gains of 1-2 cm over the full second year are typical.

Routine developmental checks

Head circumference in toddlers is measured less frequently than in infancy, typically at routine developmental checks. By age 2, the brain is approximately 80% of its adult size and the rate of head growth has slowed considerably. Continue attending all scheduled health checks, as these reviews cover development across multiple domains.

Signs that warrant review

If your toddler shows any neurological concerns - regression in speech or motor skills, unusual head shape, or significant changes in behaviour - head circumference measurement is one of several assessments a paediatrician would carry out. Early identification of any developmental concerns leads to earlier support and better outcomes.

Frequently asked questions

What is a normal head circumference for this age?

The percentile table on this page shows the full range of typical head circumferences. All values from the 5th to the 95th percentile are within normal limits. As with all growth measurements, the pattern of growth over time is more informative than any single reading - a baby growing consistently at the 15th percentile is growing normally.

How fast does head circumference grow in the first year?

Head circumference grows approximately 10-12 cm in the first year of life - roughly 2 cm per month in the first 3 months, slowing to about 1 cm per month from 3-6 months, and 0.5 cm per month from 6-12 months. By 12 months, the average head circumference has grown from approximately 34-35 cm at birth to around 46-47 cm.

What is the fontanelle and when does it close?

The fontanelle is the soft spot on the top of a baby's head where the skull bones have not yet fused. There are two fontanelles: the larger anterior (front) fontanelle, which typically closes between 9 and 18 months, and the smaller posterior (back) fontanelle, which usually closes by 2-3 months. Both allow the skull to expand rapidly as the brain grows during the first years of life.

Data sources and methodology

The percentile ranges on this page are drawn from CDC growth chart data from the National Center for Health Statistics and WHO Child Growth Standards (for children under 5). CDC data published May 30, 2000, with 2022 extended BMI tables. Percentiles are modelled using the LMS method (Box-Cox transformation), which accounts for the skewed distribution of measurements at each age. All measurements are given in metric units with imperial equivalents.

These reference ranges are for general information only. A healthcare professional can provide personalised assessment based on the individual's growth pattern.