Check your baby's length-for-age percentile using WHO growth charts. Enter age, length, and sex for instant results.
Length (height) is one of the key measurements pediatricians track to ensure healthy growth. The WHO length-for-age charts compare your baby's length to a reference population of healthy children worldwide.
For infants under 2 years, length is measured lying down (recumbent). After age 2, standing height is used. A baby at the 60th percentile for length is longer than 60% of babies the same age and sex.
This calculator uses WHO length-for-age median data for boys and girls from birth to 24 months. It provides an approximate percentile based on your baby's measurements. Use it as a guide between pediatric visits, and always rely on your doctor for clinical assessments. Whether you are a beginner or experienced professional, this free online tool provides instant, reliable results without manual computation. By automating the calculation, you save time and reduce the risk of costly errors in your planning and decision-making process. This tool handles all the complex arithmetic so you can focus on interpreting results and making informed decisions based on accurate data.
Tracking length percentile helps identify growth patterns and potential issues early. A baby who was at the 70th percentile and drops to the 20th may need evaluation. Consistent tracking ensures your baby is growing at their own healthy rate. Having a precise figure at your fingertips empowers better planning and more confident decisions.
Z-score = (Measured Length − Median Length) / Standard Deviation Percentile derived from z-score via standard normal CDF. WHO length-for-age charts: birth to 24 months, boys and girls separately.
Result: ~50th percentile
A 9-month-old girl measuring 27.5 inches (69.9 cm) is near the 50th percentile on the WHO length-for-age chart. This means she's right at the median — perfectly average for her age.
The WHO length-for-age charts track how babies grow in length relative to age. They were developed from the Multicentre Growth Reference Study, which followed healthy breastfed children in six countries to establish how children should grow under ideal conditions.
Babies don't grow at a constant rate. Growth spurts are common, especially around 3 weeks, 6 weeks, 3 months, 6 months, and 9 months. During spurts, babies may be fussier and eat more. These are temporary and normal.
Consult your pediatrician if your baby's length falls below the 3rd or above the 97th percentile, or if they cross two major percentile lines in either direction. These patterns may warrant further evaluation for growth disorders or nutritional issues.
Any percentile between the 5th and 95th is normal. What's most important is that your baby follows a consistent growth curve over time rather than jumping between percentiles dramatically.
Recumbent length (lying down) is standard for children under 2 because they cannot stand reliably. Standing height begins at age 2. Recumbent length is typically about 0.7 cm more than standing height.
Baby length is a rough indicator but not a reliable predictor of adult height. Mid-parental height calculations are more accurate. Growth patterns stabilize more between ages 2-3 when better predictions can be made.
A lower percentile isn't concerning if it's consistent and your baby is following their curve. If your baby was at the 50th percentile and dropped to the 10th, that warrants a conversation with your pediatrician.
Yes. Boys are slightly longer than girls on average at every age. That's why the WHO provides separate growth charts for each sex. Always use the correct chart for your baby.
This provides an approximation based on simplified WHO data. Clinical growth charts use continuous curves with precise percentile bands. For accurate clinical assessment, rely on your pediatrician's measurements and charting.