Check my BMI

Check your BMI in a few seconds, then see what the number means for your health and what sensible next steps look like.

80 kg
168 cm
28.3kg/m²Overweight

The healthy range for your height is about 52 kg to 70 kg. Prescription weight-loss treatment is generally considered for adults with a BMI of 30 or more, or 27 or more with a weight-related health condition — a doctor decides whether it is right for you.

CHECK IF YOU’RE SUITABLE

Free online assessment with an Irish doctor-led service. Takes about 2 minutes.

BMI is a screening tool, not a diagnosis. It does not account for muscle mass, and thresholds can differ by ethnicity (for example, health risk can start at a lower BMI in people of South Asian, Chinese or Black African background). Not for under-18s or during pregnancy.

What your result means

  • Under 18.5 (underweight): speak to your GP, especially if the weight loss was unintentional. Weight-loss treatment is not appropriate.
  • 18.5–24.9 (healthy): a healthy range for most adults. Keep an eye on waist size and fitness, which BMI does not show.
  • 25–29.9 (overweight): extra weight raises risk over time. Lifestyle changes are the first step; a doctor can advise if you also have a weight-related condition.
  • 30 or more (obesity): associated with higher risk of type 2 diabetes, high blood pressure, heart disease and sleep apnoea. Medical treatment can be considered alongside diet and activity changes.

BMI is only part of the picture

BMI does not measure body fat directly. A useful second check is waist-to-height ratio: keep your waist measurement to less than half your height. Muscular people, older adults and people from some ethnic backgrounds can have a BMI that overstates or understates their risk, which is why a doctor looks at blood pressure, blood sugar, cholesterol and your history as well.

Next steps after you check your BMI

  1. Note the number and your waist measurement, and recheck every few months rather than daily.
  2. If you are in the overweight or obesity range, start with food, activity and sleep — small, sustainable changes.
  3. If you have a BMI of 30 or more, or 27 or more with a weight-related health condition, you can ask a doctor whether prescription treatment is appropriate for you. Slimbr’s free online assessment takes about 2 minutes and a doctor decides whether treatment is suitable.
  4. If anything worries you — rapid weight change, tiredness, breathlessness — see your GP.

Frequently asked questions

How do I check my BMI?

Enter your height and weight in the calculator above — it works in kg, stone and pounds, and cm or feet and inches — and your BMI and category appear straight away.

What is a good BMI?

For most adults 18.5 to 24.9 is the healthy range. For Irish and UK adults of South Asian, Chinese or Black African background, health risk can start at a lower BMI, so ask a doctor how to read your result.

How often should I check my BMI?

Every few months is plenty. Weight fluctuates day to day, so frequent checking adds noise rather than information.

My BMI says overweight but I lift weights. Is that wrong?

It can be. BMI cannot tell muscle from fat, so a muscular person can score in the overweight range with a low body-fat percentage. Waist measurement is a better check in that case.

When should I see a doctor about my BMI?

If your BMI is under 18.5, or 30 or more, if it is 27 or more and you have a weight-related condition, or if your weight has changed quickly without explanation.

Want to see how the number is worked out? Read how to calculate your BMI, or go to the BMI calculator Ireland page.