It can be complicated to check if your child is a healthy weight as children of different ages and sexes grow and develop at different rates.
For children and young people aged 2 to 18, you can check if their weight is right for their height, using their body mass index (BMI). Adults can also use BMI to check if their weight is healthy but in a different way to children.
BMI in children is calculated by dividing their weight (in kilograms) by the square of their height (in metres), and for children, the result is given as a centile (or percentile) based on an average from national surveys. For example, a healthy weight result is between the 3rd and 91st centile.
If you are worried about your child’s weight then speak to a healthcare professional such as your health visitor, school nurse or GP.
Children are weighed and measured at school in Reception and Year 6 as part of the National Child Measurement Programme (NCMP).
Before the programme starts each school year, local authorities write to the parents and carers of all children eligible for measurement to inform them of the programme. Parents or carers can choose to withdraw their child from the process by responding to the letter.
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
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.
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.
Better Health exists to motivate and enable the nation to lead active and healthy lives. It's there to support and encourage all of us in taking steps to improve our physical and mental health.