Ideal weight calculator
There is no single ideal weight, but there is a healthy range. This tool takes the NHS BMI band of 18.5 to 24.9 and turns it into a weight range for your height, in metric or imperial.
How it works
The healthy range comes straight from the NHS definition of a healthy weight, which is a BMI of 18.5 to 24.9. BMI is weight in kilograms divided by height in metres squared, so rearranging it gives a weight for any BMI at a fixed height. The tool multiplies your height in metres squared by 18.5 for the lower figure and by 24.9 for the upper figure. Anything between those two weights sits inside the healthy band.
The Devine figure shown alongside is a separate, older method. It starts from a base weight, 45.5 kg for women and 50 kg for men, and adds 2.3 kg for every inch of height above 5 feet. It was built in the 1970s to help calculate medicine doses, not to judge general health, so it usually lands near the middle of the BMI range and is included only for context.
Worked example
Take a height of 170 cm, which is 1.7 metres. Squared, that is 2.89. Multiplying by 18.5 gives 53 kg and by 24.9 gives 72 kg, so the healthy range is about 8 st 6 lb to 11 st 5 lb. The Devine formula for a woman of this height returns 61 kg, which sits comfortably inside that range.
Common questions
What is the ideal weight for my height?
The NHS defines a healthy weight as a BMI between 18.5 and 24.9, so there is a range rather than a single number. This tool applies those two BMI values to your height to give the lower and upper healthy weight, in kilograms and stones.
Why is it a range and not one number?
People of the same height carry different amounts of muscle and build, so a healthy weight spans a band. Anywhere inside the 18.5 to 24.9 BMI range counts as healthy. Sitting in the middle is not more correct than sitting near either edge.
What is the Devine formula?
The Devine formula is an older method from 1974 that estimates an ideal weight from height and sex, starting from a base and adding 2.3 kg for each inch over 5 feet. It was designed for medicine dosing, not general health, so it is shown here only as context.
Does this work for everyone?
No. BMI is a rough guide for adults and does not suit very muscular people, pregnant women, or children, who use different growth charts. It also does not account for where fat sits. Treat the range as a starting point and speak to your GP for a fuller picture.
What if I am outside the healthy range?
Being under or over the range slightly is common and not always a concern. Larger gaps are worth discussing with your GP, who can look at waist measurement, activity and health history rather than weight alone.