Advice for health professionals

It is common practice when weighing a patient to convert the patient's weight in kilograms to stones and pounds. While some patients may request this, and you should not refuse such a request, you are urged to give the correct value in kilograms, and only offer a conversion if specifically requested to do so. Why does it help patients to give their weight in kilograms?

There are a number of reasons why you should tell patients their weight in kilograms:

  • many patients will prefer kilograms, especially the young, those who use gyms (where machines are calibrated in kg), and those born outside the UK;
  • it is quicker to do so than convert to stones/pounds;
  • it reduces the chances of errors in converting;
  • encouraging patients to understand their weight in kg allows them to easily calculate their correct weight and BMI;
  • familiarising patients with their – or their child's – weight in kg could help when there is a need to calculate medicine doses.

Finally, you should be aware that it is a legal requirement!

What is the legal position of using stones/lbs versus kg?

The position is clear: public bodies and public servants must use metric forms as the primary measure except for a small number of specific exemptions, and there are no such exemptions in the field of public health. Imperial 'supplementary indications' are allowed – which means you can give an imperial figure but this must be in addition to the kg figure.

For official guidance click here to download this PDF document (courtesy of the National Measurement Office).