Weight and health

BMI calculator

BMI compares your weight to your height. It is the number a doctor starts from when deciding whether weight-loss treatment is worth discussing — but it is a starting point, not a diagnosis.

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Your BMI appears here as you type.

What BMI means for treatment options

  • Under 27

    Diet, activity and pharmacist support are the usual route. Prescription weight-loss treatment is not normally considered at this BMI.

  • 27 to 29.9

    A doctor may consider prescription treatment if you also have a weight-related condition, such as type 2 diabetes, high blood pressure, high cholesterol or sleep apnoea.

  • 30 or over

    Prescription treatment is usually considered alongside diet and activity changes, if it is clinically suitable for you.

Only a doctor can decide whether treatment is right for you. They will review your full medical history, current medicines and health conditions before prescribing anything — BMI on its own is never enough.

Not sure what your number means?

An online doctor can review your health history and tell you whether weight-loss treatment is suitable. If it is, send the prescription to Healthwave and we will deliver discreetly anywhere in Ireland.

Talk to an online doctorWeight-loss options

What BMI does not tell you

BMI is a rough measure and it gets some people wrong:

  • It cannot tell muscle from fat, so very muscular people can read as overweight.
  • Health risk starts at a lower BMI for people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background.
  • It says nothing about where fat is carried. Waist measurement adds a lot, especially in the 25 to 30 range.
  • It is not valid during pregnancy, and children and teenagers need age and sex specific charts instead.

If you are worried about your weight or your health, talk to your GP or one of our pharmacists rather than acting on this number alone.

Categories follow the standard WHO and HSE adult BMI ranges. This tool gives a general estimate and does not replace personalised medical advice.