Population screening
BMI is a fast, cheap first pass at categorising weight across large groups. Useful in public health and clinical triage.
Metric & Imperial · Private
BMI Calculator
Body mass index with your healthy weight range, prime weight, and a visual scale — in metric or imperial units.
Your BMI
—
Enter your weight and height to see your BMI and healthy range.
The BMI Formula
Metric formula
BMI = weight (kg) ÷ height (m)²
Example: 70 kg, 1.75 m → BMI = 70 ÷ 3.0625 = 22.9.
Imperial formula
BMI = (weight (lb) × 703) ÷ height (in)²
Example: 154 lb, 69 in → BMI = (154 × 703) ÷ 4761 = 22.7.
BMI categories (WHO adult scale)
- Below 16 — Severely underweight
- 16 to 18.4 — Underweight
- 18.5 to 24.9 — Normal weight
- 25 to 29.9 — Overweight
- 30 to 34.9 — Obese Class I
- 35 to 39.9 — Obese Class II
- 40 and above — Obese Class III
Healthy weight range
The calculator shows the weight range that would put you between BMI 18.5 and 24.9 at your current height. That is the "healthy weight range" shown on many medical charts. It does not account for muscle mass, bone density, age or sex.
Prime weight (BMI 22)
A BMI of 22 is often cited as the midpoint of the healthy range and associated with the lowest all-cause mortality in large population studies. It is a reference point, not a personal goal.
What BMI cannot tell you
BMI cannot distinguish between fat and muscle. Two people with the same BMI can have very different body compositions. It also does not indicate where fat is stored — and visceral fat (around the organs) is more harmful than subcutaneous fat. For a fuller picture, doctors use waist-to-height ratio, waist circumference, body fat percentage, blood pressure, and blood tests.
Healthy Ranges by Height
| Height | Healthy weight range | Prime weight (BMI 22) |
|---|---|---|
| 150 cm (4′11″) | 41.6 – 56.0 kg (91.7 – 123.5 lb) | 49.5 kg |
| 160 cm (5′3″) | 47.4 – 63.7 kg (104.5 – 140.4 lb) | 56.3 kg |
| 170 cm (5′7″) | 53.5 – 72.0 kg (117.9 – 158.7 lb) | 63.6 kg |
| 175 cm (5′9″) | 56.7 – 76.3 kg (125.0 – 168.2 lb) | 67.4 kg |
| 180 cm (5′11″) | 59.9 – 80.7 kg (132.1 – 177.9 lb) | 71.3 kg |
| 185 cm (6′1″) | 63.3 – 85.2 kg (139.6 – 187.8 lb) | 75.3 kg |
| 190 cm (6′3″) | 66.8 – 89.9 kg (147.3 – 198.2 lb) | 79.4 kg |
When BMI is Useful
Medical forms
Some insurance, surgery and clinical trial forms ask for BMI as part of routine data collection.
Tracking change
If your weight is changing, BMI gives a consistent number to track over time — as long as height is fixed.
Not for athletes
Muscle weighs more than fat. Many fit, muscular people have a BMI in the "overweight" range while being very healthy.
Not for children
Children and teenagers need age- and sex-specific percentile charts, not the adult BMI scale.
Not during pregnancy
BMI is not meaningful during pregnancy or breastfeeding. Doctors use different charts instead.
BMI FAQ
What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is considered healthy.
Is BMI accurate for everyone?
No. BMI does not distinguish between muscle and fat, and it is not reliable for athletes, pregnant women, children, or the elderly. Use it as a rough guide only.
How is BMI calculated?
Metric: BMI = kg ÷ m². Imperial: BMI = (lb × 703) ÷ in².
What is a prime BMI?
A BMI of 22 is often cited as the midpoint of the healthy range and associated with the lowest risk in population studies. It is a common reference point, not a personal target.
Does BMI apply to children?
Not to the standard adult scale. Children and teenagers use age- and sex-specific BMI percentile charts. Consult a paediatrician for accurate assessment.
Should I use BMI to decide if I need to lose weight?
No. Speak to a doctor or dietitian. BMI is one data point among many and can be misleading on its own.
Is BMI different for men and women?
The formula is the same, but body composition differs. Some researchers suggest lower thresholds for some populations. The WHO scale used here applies to all adults.
Is my weight and height stored anywhere?
No. Everything runs in your browser. Nothing is uploaded, logged or shared. If you use a shared computer, clear the browser history to remove any URL state.
You Might Also Need
Last updated: .