BMI calculator Ireland
Free BMI calculator for adults in Ireland. Slide to your height and weight and see your BMI, your WHO category and the healthy weight range for your height. New to this? See how to calculate your BMI by hand or what to do once you have checked your BMI.
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 BMI means
Body mass index (BMI) compares your weight with your height: weight in kg ÷ height in metres squared. These are the standard World Health Organization bands for adults.
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25 – 29.9 | Overweight |
| 30 – 34.9 | Obesity (class 1) |
| 35 – 39.9 | Obesity (class 2) |
| 40 or more | Obesity (class 3) |
Healthy weight for your height
The weight range that gives a BMI of 18.5 to 24.9 at common heights:
| Height | Healthy weight (kg) | Healthy weight (stone) |
|---|---|---|
| 4′11″ (150 cm) | 42–56 kg | 6 st 8 lb – 8 st 11 lb |
| 5′0″ (152 cm) | 43–58 kg | 6 st 11 lb – 9 st 1 lb |
| 5′2″ (157 cm) | 46–62 kg | 7 st 3 lb – 9 st 10 lb |
| 5′4″ (163 cm) | 49–66 kg | 7 st 10 lb – 10 st 5 lb |
| 5′6″ (168 cm) | 52–70 kg | 8 st 3 lb – 11 st |
| 5′8″ (173 cm) | 55–74 kg | 8 st 10 lb – 11 st 10 lb |
| 5′10″ (178 cm) | 58–79 kg | 9 st 3 lb – 12 st 6 lb |
| 6′0″ (183 cm) | 62–83 kg | 9 st 10 lb – 13 st 2 lb |
| 6′2″ (188 cm) | 65–88 kg | 10 st 4 lb – 13 st 12 lb |
| 6′4″ (193 cm) | 69–93 kg | 10 st 12 lb – 14 st 9 lb |
BMI calculator FAQs
How do I calculate my BMI?
BMI is your weight in kilograms divided by your height in metres, squared (kg ÷ m²). For example, 80 kg at 1.68 m is 80 ÷ (1.68 × 1.68) = 28.3. The calculator above does this for you as you move the sliders, in kg, stone and pounds, and cm or feet and inches.
What is a healthy BMI?
For most adults the healthy range is a BMI of 18.5 to 24.9. Under 18.5 is underweight, 25 to 29.9 is overweight, and 30 or more is classed as obesity (30–34.9 class 1, 35–39.9 class 2, 40+ class 3).
Is BMI accurate?
BMI is a quick screening tool, not a diagnosis. It cannot tell muscle from fat, so very muscular people can score high, and it does not show where fat is carried. Health risk can also begin at a lower BMI in people of South Asian, Chinese and Black African background. A doctor looks at BMI alongside waist size, blood pressure, blood sugar and your history.
What BMI do you need for weight-loss medication in Ireland?
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 such as type 2 diabetes, high blood pressure or sleep apnoea. Whether it is right for you is always a doctor’s decision after a proper assessment.
Does BMI work for children, teenagers or in pregnancy?
No. This calculator is for adults aged 18 and over who are not pregnant. Children and teenagers are assessed on growth charts for their age, and BMI is not used during pregnancy.
Want the full explanation, including how BMI relates to treatment options in Ireland? Read our BMI calculator guide for Ireland.