BMI Calculator (Metric)

Q: What is a healthy BMI in metric units?

18.5 to 24.9, the same as in imperial — BMI is unitless. At 170 cm that means 53 to 72 kg.

Q: What is a BMI of 27 in kilograms?

It depends on height: at 170 cm a BMI of 27 is about 78 kg; at 160 cm it's about 69 kg; at 180 cm it's about 87 kg.

Height

Weight

Your BMI

27.0

WHO category: Overweight
Healthy weight range for your height: 53 – 72 kg
Where you are: 6 kg above the healthy range
BMI at the edges of that range: 53 kg → 18.5 · 72 kg → 24.9

Healthy weight range at nearby heights

Height	BMI 18.5	BMI 24.9	Healthy range
160 cm	47 kg	64 kg	47 – 64 kg
165 cm	50 kg	68 kg	50 – 68 kg
170 cm	53 kg	72 kg	53 – 72 kg
175 cm	57 kg	76 kg	57 – 76 kg
180 cm	60 kg	81 kg	60 – 81 kg

BMI is a ratio of weight to height, not a measure of body fat — it reads high on heavily muscled bodies and low on people who have lost muscle. Need feet and pounds instead? Use the BMI calculator in US units; for a height-only target weight see the ideal weight calculator.

At 170 cm and 78 kg your BMI is 27.0 — the WHO "overweight" band. The healthy weight range for 170 cm is 53–72 kg, so getting inside it means losing 6 kg. For reference, 165 cm with 60 kg is a BMI of 22.0 (normal weight) and 185 cm with 95 kg is 27.8 (overweight). This version takes centimetres and kilograms only — no unit switching.

The formula

BMI = weight (kg) ÷ height (m)²

At 170 cm and 78 kg: 1.70² = 2.89, and 78 ÷ 2.89 = 27.0.

That's the entire calculation. BMI has no adjustment for age, sex, or body composition — which is both why it's useful at population scale and why it's crude for individuals.

What counts as what

BMI	WHO category
Below 18.5	Underweight
18.5 – 24.9	Normal weight
25.0 – 29.9	Overweight
30.0 – 34.9	Obesity class I
35.0 – 39.9	Obesity class II
40.0 and above	Obesity class III

The thresholds are identical for men and women, and they're set in BMI units rather than kilos on purpose — they apply across every height.

The healthy weight range for your height

Because BMI 18.5–24.9 maps to a weight range at any given height, the calculator reverses the formula to show yours. For heights around 170 cm:

Height	BMI 18.5	BMI 24.9	Healthy range
160 cm	47 kg	64 kg	47 – 64 kg
165 cm	50 kg	68 kg	50 – 68 kg
170 cm	53 kg	72 kg	53 – 72 kg
175 cm	57 kg	76 kg	57 – 76 kg
180 cm	60 kg	81 kg	60 – 81 kg

Five centimetres of height moves the top of the range by about 4 kg. That's why comparing your weight to someone else's tells you nothing.

What BMI doesn't measure

Muscle. A lean, heavily trained 170 cm bodybuilder at 85 kg reads as BMI 29.4 — nearly "obese" — while carrying 10% body fat.
Where the fat is. Visceral fat around the organs carries more risk than fat on hips and thighs, and BMI can't tell them apart. Waist circumference does.
Age. Older adults lose height and muscle, so the same BMI means something different at 30 and at 75.
Children. Under 18, BMI is read against age- and sex-specific percentile charts, not these bands.

For a ratio that knows about body fat, use the body fat calculator; for a target weight based on height alone, the ideal weight calculator. If you need feet and pounds instead of centimetres, the US-units BMI calculator does the same maths with a unit switch.

How to use this calculator

Enter your height in centimetres.
Enter your weight in kilograms.
Read your BMI, your WHO category, and your healthy range.
Check the nearby-heights table if you want to see how the range shifts.
If you're outside the range, treat the difference as a direction, not a deadline.

Frequently asked questions

What is a healthy BMI in metric units?

18.5 to 24.9, the same as in imperial — BMI is unitless. At 170 cm that means 53 to 72 kg.

What is a BMI of 27 in kilograms?

It depends on height: at 170 cm a BMI of 27 is about 78 kg; at 160 cm it's about 69 kg; at 180 cm it's about 87 kg.

Is BMI accurate for everyone?

No. It overstates risk for muscular people and understates it for people who have lost muscle with age. It's most useful as a screening number, paired with a waist measurement.

How much do I need to lose to reach a normal BMI?

Your current weight minus the top of your healthy range. At 170 cm and 78 kg, that's 78 − 72 = 6 kg. At 185 cm and 95 kg, it's 95 − 85 = 10 kg.

Data sources: BMI is weight in kilograms divided by height in metres squared. Category boundaries are the World Health Organization adult classification (underweight below 18.5, normal 18.5–24.9, overweight 25–29.9, obesity class I 30–34.9, class II 35–39.9, class III 40 and above). Healthy weight ranges are computed by solving BMI = 18.5 and BMI = 24.9 for weight at the entered height, then rounded to the nearest kilogram. All figures are reproducible from the default inputs (170 cm, 78 kg).

Disclaimer: This calculator is a general screening estimate and is not medical advice. BMI does not measure body fat, fitness, or health, and it reads inaccurately for athletes, older adults, pregnant people, and children. If you are considering a significant change in weight, or if you have a condition affected by weight, talk to a clinician. Related tools: BMI calculator in US units, body fat calculator, ideal weight calculator, all health calculators.