Rob,
Just to note I think the NHS Choices BMI tool has a rounding error. The BMI
calculated via NHS Choices for an adult of 180 cm and weight of 80 kg is
24.6. If you use the healthy living assessment that we have developed at
LTHT (see
http://forms4care.com/XForm/LoadForm?patientId=2&formName=Healthy-Living-Assessment)
it comes up with 24.69 (or 24.7 to the same number of significant figures).
I have also manually done the calculation BMI = weight (kg) / height (m) x
height (m) = 80 / 3.24 = 24.691…
Mike