Quick answer: At 170 cm the healthy range tops out at 24.9 × 1.70² = 72.0 kg, so a weight of 85 kg (BMI 29.4, overweight) is 13.0 kg above the range.
How it's calculated
Your BMI is weight (kg) ÷ height (m)². The WHO classes 25 to 29.9 as overweight and 30 and above as obesity. The healthy range for your height is the weight that gives a BMI from 18.5 to 24.9.
The calculator measures the gap to the nearest edge of that range: above it, the kilos over 24.9 × height²; below it, the kilos under 18.5 × height². Some calculators put the top of the range at 25 instead of 24.9, which moves the edge by about 0.3 kg. It also shows the weight at BMI 30, the line between overweight and obesity.
BMI cannot tell fat from muscle or say where fat is stored. Fat around the waist carries more risk than the same weight on the hips, so waist size is a useful second check. The number is also not meant for children, pregnancy or very muscular people. See the healthy weight calculator for the full range table.
Worked examples
- 85 kg, 170 cm: BMI 29.4; 85 − 72.0 = 13.0 kg above
- 95 kg, 175 cm: BMI 31.0; 95 − 76.3 = 18.7 kg above
- 65 kg, 170 cm: BMI 22.5, within 53.5 – 72.0 kg
WHO adult BMI categories
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25 – 29.9 | Overweight (pre-obesity) |
| 30 – 34.9 | Obesity class I |
| 35 – 39.9 | Obesity class II |
| 40 and above | Obesity class III |
Frequently asked questions
At what BMI are you overweight?
For adults, a BMI of 25 to 29.9 is overweight and 30 or more is obesity in the WHO classification.
Why does it measure to 24.9 and not to an ideal weight?
Any weight inside the range counts as healthy for the height, so the distance to the nearest edge is the smallest change that reaches it.
Can I be overweight by BMI but healthy?
Yes, especially with a lot of muscle. Waist circumference, blood pressure, blood sugar and cholesterol give a fuller picture.
How much weight do I need to lose to see a benefit?
Even 5–10% of your body weight can improve blood pressure and blood sugar. At 85 kg that is about 4 to 8.5 kg, well short of the top of the healthy range.
Does my waist size matter too?
Yes. Fat around the waist carries more health risk. WHO links higher risk to a waist above 94 cm in men and 80 cm in women.
How fast is it safe to lose weight?
About 0.5 to 1 kg a week is the usual advice. Faster loss may need medical supervision and is harder to keep off.