Free tool
BMI calculator
Check your BMI, the category it falls in, and the weight range that's considered healthy for your height.
Your BMI
24.2Healthy weight
Healthy range for your height
53.5 kg – 72.0 kg
Distance from that range
In range
Your weight already falls inside it
Estimates, not medical advice. BMI is a screening number, not a diagnosis, and it says nothing about your body composition or health. It is not valid for children, pregnancy, or elite athletes. Use it as one data point among several.
What BMI actually measures
BMI is weight scaled to height, and that’s all. It was devised in the 1830s by a Belgian statistician studying populations, not patients, and it was never designed to assess an individual. Its survival for two centuries is a story about convenience: you need one scale, one tape measure, and no laboratory.
That convenience is also the limitation. Two people with identical BMIs can have completely different amounts of muscle, fat, and bone, and different distributions of it — which is the part that actually predicts health outcomes.
Where BMI misleads
- Muscle reads as fat. Lean, strong people are frequently classified as overweight.
- It ignores where fat sits. Visceral fat around the organs carries more risk than the same weight on hips and thighs, and BMI cannot tell them apart.
- It ages badly. Older adults lose muscle and gain fat at a stable weight, so an unchanged BMI can hide a real shift.
- The thresholds aren’t universal. Several health bodies use lower cut-offs for people of South Asian descent, because metabolic risk appears at a lower BMI.
A more useful pairing
Take a waist measurement alongside your BMI. A waist circumference over roughly 94 cm (37 in) for men or 80 cm (31.5 in) for women is associated with elevated risk regardless of what BMI says, and the combination of the two catches most of what BMI alone misses.
For tracking your own progress, the direction matters more than the category. A BMI drifting down over months while your strength holds steady is a good sign; a single reading on one morning is noise.
If you want a number you can actually act on, the TDEE calculator turns your height and weight into a daily calorie target, and the fasting calculator sets the window to eat it in.
Common questions
How is BMI calculated?+
BMI is your weight in kilograms divided by your height in metres squared. In imperial units it's weight in pounds divided by height in inches squared, multiplied by 703. That's the whole formula — it uses no other information about you.
What is a healthy BMI?+
The World Health Organization classifies adult BMI under 18.5 as underweight, 18.5 to 24.9 as healthy weight, 25 to 29.9 as overweight, and 30 or above as obese. These thresholds were derived from population data on white adults and fit some populations better than others.
Is BMI accurate for athletes?+
No. BMI cannot distinguish muscle from fat, so a muscular person is routinely classified as overweight or obese despite low body fat. If you lift seriously or play a strength sport, BMI is close to meaningless for you — waist measurement or a body composition scan is far more informative.
Should I use BMI or body fat percentage?+
Body fat percentage tells you more, but it's harder to measure accurately outside a clinic. BMI is useful precisely because it's cheap and consistent — as a rough population-level screen, and as something you can track over time. Paired with a waist measurement, it gets meaningfully more useful.
Does BMI work for children?+
Not in this form. Children and teenagers are assessed with age- and sex-specific percentile charts, because healthy body composition changes substantially through growth. This calculator is for adults.
One number is noise
Watch the trend, not the morning.
Fastiq charts weight and BMI over weeks, next to your fasting streak and macro averages, so you can see what's actually working.
