Baby Growth Percentile Calculator by Week

Tracking your baby's growth percentiles by week helps parents monitor development and identify potential concerns. This calculator uses standard growth charts to determine where your baby's measurements fall compared to other babies of the same age.

How to Use This Calculator

To calculate your baby's growth percentile:

Enter your baby's age in weeks (0-52)
Select the measurement type (length, weight, or head circumference)
Enter your baby's measurement in the appropriate units
Click "Calculate" to see the percentile result

The calculator uses standard WHO growth charts for infants. Percentiles indicate where your baby's measurement falls compared to other babies of the same age:

Below 5th percentile: Below average growth
5th-85th percentile: Average growth
Above 85th percentile: Above average growth

Note: Percentiles are not the same as percentages. A 50th percentile means your baby is at the 50th percentile, not 50% of the population.

Interpreting Results

Understanding your baby's growth percentile helps you monitor development and identify potential concerns. Here's what different percentiles mean:

Percentile Range	Interpretation	Action
Below 5th	Below average growth	Consult pediatrician
5th-85th	Average growth	Monitor regularly
Above 85th	Above average growth	Monitor for rapid growth

If your baby's measurements consistently fall below the 5th percentile, it's important to consult with your pediatrician. Rapid growth changes should also be monitored.

Baby Growth Milestones

Here are some typical growth milestones by week:

Week	Length	Weight	Head Circumference
0-4	20-22 inches	5.5-7.5 lbs	12.5-13 inches
4-8	22-24 inches	7.5-10 lbs	13-13.5 inches
8-12	24-26 inches	10-12 lbs	13.5-14 inches
12-16	26-28 inches	12-14 lbs	14-14.5 inches

These are general guidelines. Individual growth patterns vary significantly. Always consult your pediatrician for personalized advice.

Frequently Asked Questions

What is a growth percentile?

A growth percentile indicates where your baby's measurement falls compared to other babies of the same age. For example, a 50th percentile means your baby is at the 50th percentile, not 50% of the population.

When should I be concerned about my baby's growth?

Consult your pediatrician if your baby's measurements consistently fall below the 5th percentile or if you notice rapid growth changes. These could indicate potential health concerns.

How often should I track my baby's growth?

Track growth at every well-child visit (typically every 2-4 weeks in the first year). You can also use this calculator between visits to monitor progress.

What if my baby's measurements are above the 85th percentile?

Above average growth is normal in the first few months. However, very rapid growth should be monitored by your pediatrician. Maintain regular checkups to ensure healthy development.