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Children's weight

"How much should my child weigh?" is a common question for parents. Our children are weighed regularly as babies, but as children grow and develop at different rates it's not always easy to tell if they are a healthy weight.

How to check your child is a healthy weight

For children and young people aged 2 to 18, you can check their weight by working out their body mass index (BMI) using the NHS BMI calculator.

A child's BMI tells us if their weight is right for their height, and the result is given as a centile (or percentile). For example, a healthy weight result is between the 3rd and 91st centile.

The BMI calculator takes into account age and sex, as well as height and weight.

If you are concerned about your child's weight or growth, contact a GP or school nurse.

School height and weight checks

Children are weighed and measured at school in Reception and Year 6 as part of the National Child Measurement Programme (NCMP).

Their height and weight are measured and used to calculate their body mass index (BMI). This information is used to plan and provide better services for children and families.

Have you received a letter from your child's school?

If your child's just been measured at school, the results can sometimes be surprising, but they're just a snapshot of your child's weight at that moment in time.

If you are worried, speak to your GP or school nurse for advice and support. You can also call the number on the results letter for advice and support.

How to check your child's result

You can use the NHS BMI calculator to check your child’s result, and see if it changes as they grow.

Should you talk to your child about their result?

This is entirely up to you. The letter is sent to you, and the school will not tell your child the result.

Some parents decide to tell their children and talk about the changes they need to make together. Others decide not to, as younger children may be less able to understand, and it might be simpler to make lifestyle changes without talking to them.

If you decide to speak to your child, talking openly about weight can help to build trust and reassure your child that it is not something to feel ashamed about.

Here are some tips that can help you talk about weight:

  • avoid blame – focus instead on the healthy things you and your family can do
  • talk about weight in a kind and supportive way
  • talk about how weight is important for health, energy and what the body can do
  • teach your child that everyone deserves respect – whatever their body size, shape or ability

Very overweight

Very overweight children tend to grow up to be very overweight adults, which can lead to health problems.

If your child is very overweight, there's lots you can do to help them become a healthier weight as they grow. Getting them to be more active and eat well is important.

How to help your child become a healthier weight


More young children than ever are overweight, but it's not always easy to tell if toddlers and very young children are overweight.

As a parent, there's plenty you can do to help your child become a healthier weight, like getting them eating well and increasing their activity levels.

How to help your child become a healthier weight

Healthy weight

If your child is already a healthy weight, there are lots of things you can do as a parent to help your child stay at a healthy weight as they grow.

Keep encouraging your child to eat well and move more, and they are more likely to stay a healthy weight.

You can also check their BMI every now and then using the NHS BMI calculator to make sure they stay in the healthy range.

How to help your child stay at a healthy weight


If you're concerned your child is underweight, take your child to see your GP. Low weight can occur for a number of reasons.

If there is a possible problem with your child's diet, your GP can give advice on what will help bring them up to a healthy weight, or refer your child to a dietitian.

You can check your child's height and weight to see if they have moved into the healthy range as they grow using the NHS BMI calculator.

Find out more:

6 ways to help your child with their weight

Small lifestyle changes can make a big difference – try these top tips.

1. Find some support

Speak to your child's school nurse, GP or practice nurse who will help support your family with diet and lifestyle changes if needed.

Find a GP

2. Make some healthier food swaps

There are lots of easy ways to cut back on sugar, salt and saturated fat – get started with our top tips and simple swaps.

Visit Food Facts

3. Eat balanced meals

Find out what a healthy, balanced diet looks like.

See the Eatwell Guide

4. Try some new recipes

Get inspiration to help your family eat well every day.

Browse our healthier recipes

5. Get moving

Try boosting your family's activity levels in 10-minute bursts with our Disney inspired playalong games.

Play a 10 Minute Shake Up game

6. Less screen time, better sleep

Sitting around too much makes it more more likely your child will put on weight, and can affect how well they sleep. Sleeping well helps kids develop, stay healthy and perform better at school.

The Sleep Charity: relaxation tips

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Join today and track your progress over 8 weeks to help your family cut down on sugar, enjoy cooking together, get their 5 A Day and move more. Taking one small step after another soon adds up to a big difference!