Our growth percentile calculator shows how your baby's size compares with other boys or girls the same age. Just enter your child's weight, height (i.e. length), and head circumference, and we'll calculate a percentile for each.
The number reflects what percentage of babies is larger or smaller than your baby. So if your 3-month-old is in the 40th percentile for weight, that means 40 percent of 3-month-old babies weigh less than your baby, and 60 percent weigh more.
When you take your baby for his well-baby visits, the nurse or doctor will weigh him, and measure his head circumference and his length. Your baby’s measurements will be recorded as dots on his growth charts, kept at the doctor's office. These dots can be joined together to show your baby’s growth curve.
Don't be concerned if your child doesn't fall in the middle of the growth chart, though. There's a wide range of normal, and your baby's measurements now don't necessarily reflect what size they'll be as an adult.
It's normal for some children to be in the 10th percentile for weight, while others are in the 90th percentile. The most important thing is that your baby is growing at a healthy and consistent rate, no matter what percentile they're in.
Using our baby growth chart
Our growth percentile calculator is an educational tool only. It's not the last word on how your child is growing, and it's not a substitute for having regular check ups with your GP or health visitor. They will check whether your child is following a healthy growth pattern over time.
This tool is for children under age 2 and is based on World Health Organisation data for children in that age group. You can also find out how tall your older child is likely to be with our child height predictor.
Accurate measurements of your baby's growth are best left to the professionals. But if you want to see how your baby is growing between your well baby appointments, here's how to get estimates at home.
Baby weight
- Undress your baby completely (remove their nappy too). Stand on scales while you're holding your child. Record that weight.
- Put your baby down and weigh yourself. Subtract your own weight from your combined weight with your baby and record that number.
- This isn't as accurate as weighing your baby at the clinic, but it's a good estimate of how much your little one weighs.
- If you're worried that your baby isn’t growing at the right rate for him, don’t hesitate to contact your. They can weigh your baby, and can offer reassurance and advice.
Baby height
Before your baby can stand and walk on their own, height is often recorded as length, that is, how long your baby is from the crown of the head to the bottom of the heel while lying down. If you want to measure your baby's length at home, here's how:
- Lay your baby down on a flat surface and stretch a measuring tape from the top of their head to the bottom of one of their heels. Babies' knees naturally bend a bit so you may need a second person to gently stretch out their legs while you take the measurement.
- Record your child's length to the nearest centimetre.
Baby head circumference
Your doctor or nurse will measure head circumference regularly, but not necessarily at every check-up. This is to make sure your baby's brain is growing at a healthy rate. You can measure your baby's head circumference at home too, but it can be hard to do accurately. Here's how to get a good estimate:
- Wrap a flexible measuring tape around the widest part of your baby's head, just above the eyebrows and ears and around the back, where the head slopes out from the neck.
- Take the measurement three times (your baby may be wiggly, which could make getting an accurate measurement tricky) and use the largest measurement to the nearest millimetre.
