BMI calculator
BMI Calculator
Get your body mass index, the World Health Organization category it falls into, and the healthy weight range for your height — in metric or imperial, instantly.
58.6–78.9 kg
A BMI of 18.5–24.9 maps to this range.
BMI is a population screening tool, not a diagnosis or a measure of body fat. This result is for general information only and is not a substitute for medical advice.
What BMI does and doesn't tell you
Body mass index is a quick screen that relates your weight to your height. It was designed in the 19th century to study populations, not individuals, and that's still its best use: across large groups, a higher average BMI tracks with higher rates of certain health risks. For one person on one day, it's a rough signal — useful, but limited.
The biggest limitation is that BMI can't see what your weight is made of. Muscle is denser than fat, so a lean, well-trained lifter and an untrained person of the same height and weight will share a BMI despite looking and being completely different. That's why so many athletes land in the "overweight" band while carrying single-digit body fat. BMI also ignores where fat sits — abdominal fat carries more risk than fat on the hips — and it isn't adjusted for age, sex or ethnicity.
So how should you use it? As a starting reference, not a target. If your BMI is well outside the normal range and you don't carry a lot of muscle, it's a reasonable prompt to look closer at your habits. But pair it with measurements that capture body composition — waist circumference, progress photos, how lifts and conditioning are trending — and judge the direction of travel over weeks, not a single reading. The number that matters is the one that's moving the way you want it to.
FAQ
Frequently asked questions
- How is BMI calculated?
- BMI equals your weight in kilograms divided by the square of your height in metres (kg/m²). For example, an 80 kg person who is 1.78 m tall has a BMI of 80 ÷ (1.78 × 1.78) = 25.2. This calculator handles the conversion from feet, inches and pounds for you.
- What is a healthy BMI?
- The World Health Organization classifies a BMI of 18.5 to 24.9 as normal weight, below 18.5 as underweight, 25 to 29.9 as overweight, and 30 or above as obese. These bands are population screening tools, not individual diagnoses.
- Is BMI accurate for athletes and lifters?
- Not always. BMI only uses height and weight, so it can't tell muscle from fat. A muscular athlete can register as 'overweight' or 'obese' while carrying very little body fat. If you train seriously, treat BMI as one coarse data point and rely more on body composition, measurements and how your clothes fit.
- What should I do if my BMI is outside the normal range?
- A single number isn't a verdict. Look at the trend over time, your waist measurement, your activity, and how you feel. If you want to change your weight, set a calorie target, prioritise protein and strength training, and track the trend. For health concerns, speak with a doctor.
Grind Track
Track this in the app
BMI is a snapshot; progress is a trend. Grind Track tracks bodyweight, strength and measurements together so you see body composition change, not just a single number. Free to start on iPhone.