What does this tool help you learn?

This tool calculates your child's body mass index (BMI), which provides a way to estimate the effect of weight on health. This tool also gives you your child's percentile on a growth chart. The percentile is the number that ranks your child's BMI among the BMIs of children of the same gender and age. Taking several BMI measurements over time can help you and your doctor assess your child's growth.

This tool can be used for children ages 2 through 19. Be cautious if you use this tool or any height and weight charts to assess your child's growth after he or she reaches puberty. Check with your doctor if you have questions.

Centers for Disease Control and Prevention (2011). Healthy weight—It's not a diet, it's a lifestyle! About BMI for children and teens. Available online: http://www.cdc.gov/healthyweight/assessing/bmi/childrens_bmi/about_childrens_bmi.html.

What do the results mean?

If your child is on the very low end of the percentile scale (for example, the 5th percentile), you may be concerned that your child is too small. This may be normal for your child. But if you are concerned, talk to your doctor. Your doctor can check your child to make sure that he or she is growing as expected.

Often parents of very small children push their children to eat more because they are concerned about their growth. This can cause problems. The child may eat less. Talk about your child's weight with your doctor. As long as your child is growing normally, you can relax a little about feeding him or her.

If your child is on the upper end of the percentile scale (for example, the 95th percentile), you may be concerned that your child is too big. This may be normal for your child. But if you are concerned, talk to your doctor. Your doctor can check your child to make sure that he or she is growing in a healthy way.

Parents of larger children are sometimes tempted to feed their child less food, to keep them from gaining too much weight. This doesn't work. When food has been restricted, the child may overeat when he or she gets the chance. Again, it is good to discuss your child's weight with a doctor who can help you see if your child's growth is within his or her normal pattern.

Your child's growth over time is the most important thing to think about when you are concerned about what your child's weight should be at any age. Your child's doctor will decide what your child's weight should be, based on what your child's growth pattern has been over time.

If you print a boy or girl growth chart, use the steps that follow. Then keep the chart so that you can track your child's percentile for several years.

1. Use this tool to find your child's BMI about once a year or as often as your doctor suggests.
2. Find your child's BMI on the side of the chart.
3. Find your child's age on the bottom of the chart.
4. Find the point where BMI and age meet. Your child's percentile will be in one of the shaded areas. Follow the curved line to the right to estimate the percentile.
5. On your child's growth chart, mark your child's percentile.

What's next?

Talk with your doctor about what your child's BMI means. Remember that BMI-for-age is just a guide. Your doctor can give you steps to take to help your child reach and stay at a healthy weight. These may include providing healthy foods and helping your child be active for certain amounts of time.

For more information, see these topics:

• Growth and Development, Ages 2 to 5 Years
• Growth and Development, Ages 6 to 10 Years
• Growth and Development, Ages 11 to 14 Years
• Growth and Development, Ages 15 to 18 Years
• Healthy Eating for Children