Our free BMI calculator tells you your body mass index in a few seconds, using kg and cm or feet, inches and pounds. Unlike most calculators online, it uses South Asian cut-offs by default. That matters, because people from Pakistan, India and Bangladesh tend to develop diabetes and heart problems at a lower BMI than Europeans. Below you will learn exactly how BMI is worked out, what your number means, what a healthy weight for your height looks like, and what to do next.
What is BMI (body mass index)?
Body mass index, or BMI, is a simple number that compares your weight to your height. Doctors, the World Health Organization (WHO) and health services around the world use it as a quick first check of whether your weight is likely to be healthy for your height.
BMI does not measure body fat directly. Instead, it gives a rough estimate that works well for most adults in large groups. For one person, it is a starting point for a conversation, not a final verdict. That is why we also explain its limitations further down and point you to tools that fill the gaps.
According to the WHO fact sheet on obesity and overweight, more than a billion people worldwide are now living with obesity. Pakistan is part of that trend, especially in cities where desk jobs, motorbikes and cars have replaced walking and physical work.
How to use this BMI calculator
The tool at the top of this page needs only your height and weight. Here is how to get an accurate result:
- Choose your units. Use the units toggle to pick Metric (height in cm, weight in kg) or Imperial (height in feet and inches, weight in pounds). This makes it both a BMI calculator in kg and a BMI calculator in feet and inches.
- Enter your height. Measure without shoes, standing straight against a wall. In Imperial mode, enter feet in one box and inches in the other (for example 5 ft and 7 in).
- Enter your weight. Weigh yourself in the morning, after using the toilet and before breakfast, in light clothing. This gives the most consistent number.
- Keep "Use South Asian cut-offs" on (or switch it off). It is ON by default. Leave it on if you are of Pakistani, Indian, Bangladeshi, Sri Lankan or other Asian heritage. Switch it off to see the standard WHO categories.
- Read your results. You will see your BMI (rounded to one decimal place), your category, a colour gauge, the healthy weight range for your height, and how many kg you would need to lose or gain to reach that range.
The calculator is designed for adults aged 18 and over. Children and teenagers need a different method, which we cover below.
The BMI formula, with worked examples
You do not need to do any maths, because the BMI calculator does it for you. Still, it helps to understand the BMI formula so you can trust the result.
Metric formula (kg and metres)
BMI = weight in kg ÷ (height in metres × height in metres)
Worked example: Ali weighs 70 kg and is 170 cm tall.
- Convert height to metres: 170 cm = 1.70 m
- Square the height: 1.70 × 1.70 = 2.89
- Divide weight by that number: 70 ÷ 2.89 = 24.2
Ali's BMI is 24.2. Under the WHO standard scale, that is "healthy". Under South Asian cut-offs, it is "overweight", because the Asian healthy range ends at 22.9. This single example shows why the toggle matters so much for Pakistani users.
Imperial formula (pounds and inches)
BMI = (weight in lb ÷ (height in inches × height in inches)) × 703
Worked example: Sara weighs 154 lb and is 5 ft 7 in tall.
- Convert height to inches: (5 × 12) + 7 = 67 inches
- Square the height: 67 × 67 = 4,489
- Divide weight by that number: 154 ÷ 4,489 = 0.0343
- Multiply by 703: 0.0343 × 703 = 24.1
Sara's BMI is 24.1. The 703 is simply a conversion factor that makes the imperial answer match the metric one. Tiny differences (24.1 vs 24.2) come from rounding.
BMI chart: WHO standard vs South Asian cut-offs
This BMI chart shows both sets of categories side by side. Our calculator uses exactly these thresholds.
| Category | WHO standard BMI | South Asian / Asian BMI |
|---|---|---|
| Underweight | Below 18.5 | Below 18.5 |
| Healthy weight | 18.5 – 24.9 | 18.5 – 22.9 |
| Overweight | 25.0 – 29.9 | 23.0 – 27.4 |
| Obese class I | 30.0 – 34.9 | 27.5 and above (obese) |
| Obese class II | 35.0 – 39.9 | |
| Obese class III | 40.0 and above |
The South Asian cut-offs come from a WHO Expert Consultation published in 2004, which looked at Asian populations and found that health risks rise at lower BMI values. They are used in Pakistani and Indian clinical guidance. The UK's NHS also applies them: its NHS guide to obesity says people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background are overweight from a BMI of 23 and obese from 27.5.
Why South Asians have different BMI cut-offs
If you have ever wondered why a slim-looking uncle has diabetes, this section explains it. BMI for Asians is interpreted differently for three main reasons.
1. More body fat at the same BMI
Research consistently shows that at the same BMI, South Asians tend to carry a higher percentage of body fat and less muscle than white Europeans. Two people can both have a BMI of 24, but the South Asian person is likely to have more fat on their body.
2. Fat is stored around the belly and organs
South Asians are more likely to store fat around the waist and inside the abdomen, around the liver and other organs. This "visceral" fat is the most harmful kind. It is closely linked to insulin resistance, type 2 diabetes, high blood pressure and heart disease. Many Pakistanis have a "thin outside, fat inside" body type.
3. Diabetes and heart disease start earlier
Because of this, South Asians often develop type 2 diabetes and heart disease at younger ages and lower body weights. The International Diabetes Federation ranks Pakistan among the countries with the highest rates of diabetes in the world. Using a stricter healthy BMI range of 18.5 to 22.9 helps catch risk earlier, when lifestyle changes work best.
Daily habits make this worse. A typical desi diet can be heavy in white rice, refined-flour roti and naan, ghee, fried snacks like samosa and pakora, mithai, and several cups of chai with sugar. Add long hours of sitting, and weight gathers quickly around the middle.
Healthy weight for my height: quick reference table
Want to know your healthy weight for your height without typing anything? Find your height below. The table shows the weight range for both the standard healthy BMI range (18.5–24.9) and the South Asian healthy range (18.5–22.9). Numbers are calculated exactly and rounded to the nearest whole kg, with pounds alongside.
| Height (cm) | Height (ft/in) | Healthy weight, WHO (BMI 18.5–24.9) | Healthy weight, South Asian (BMI 18.5–22.9) |
|---|---|---|---|
| 150 cm | 4 ft 11 in | 42 – 56 kg (92 – 124 lb) | 42 – 52 kg (92 – 114 lb) |
| 155 cm | 5 ft 1 in | 44 – 60 kg (98 – 132 lb) | 44 – 55 kg (98 – 121 lb) |
| 160 cm | 5 ft 3 in | 47 – 64 kg (104 – 141 lb) | 47 – 59 kg (104 – 129 lb) |
| 165 cm | 5 ft 5 in | 50 – 68 kg (111 – 149 lb) | 50 – 62 kg (111 – 137 lb) |
| 170 cm | 5 ft 7 in | 53 – 72 kg (118 – 159 lb) | 53 – 66 kg (118 – 146 lb) |
| 175 cm | 5 ft 9 in | 57 – 76 kg (125 – 168 lb) | 57 – 70 kg (125 – 155 lb) |
| 180 cm | 5 ft 11 in | 60 – 81 kg (132 – 178 lb) | 60 – 74 kg (132 – 164 lb) |
| 185 cm | 6 ft 1 in | 63 – 85 kg (140 – 188 lb) | 63 – 78 kg (140 – 173 lb) |
Feet-and-inch values are rounded to the nearest inch. If your height falls between two rows, the BMI calculator above will give you your exact range. For a second opinion using classic ideal-weight formulas, try our ideal weight and waist-to-height calculator.
BMI for men and women: is there a difference?
The BMI formula and categories are the same for adult men and women. The calculator does not ask for your sex, because it would not change the number.
That said, women naturally carry more body fat than men at the same BMI, and men tend to have more muscle. So a man and a woman with an identical BMI of 23 may have quite different body compositions. Waist size helps here: South Asian men are at increased risk from a waist of 90 cm and women from 80 cm.
Age matters too. As we get older, we tend to lose muscle and gain fat, even if our weight stays the same. So a "healthy" BMI at 65 can hide more fat than the same BMI at 25.
Limitations of BMI: when the number can mislead
BMI is useful, cheap and quick, but it has real blind spots. Knowing the BMI limitations helps you read your result sensibly.
- Muscle weighs more than fat. Gym-goers, wrestlers, cricketers and labourers with lots of muscle can show as "overweight" or even "obese" while having little body fat.
- Older adults. Muscle loss with age means BMI can underestimate body fat in the elderly. Some doctors accept a slightly higher BMI in people over 65, as being a little heavier can protect against frailty.
- Pregnancy. BMI is not valid during pregnancy, because weight gain is expected and healthy. Use your pre-pregnancy BMI and follow your doctor or Lady Health Visitor's advice on weight gain.
- Children and teenagers. Under 18s should not use adult cut-offs. They need BMI-for-age percentiles, which compare a child with others of the same age and sex. A paediatrician can plot these on a growth chart.
- It ignores where fat sits. Two people with the same BMI can have very different risk if one carries weight on the hips and the other around the belly. Belly fat is the bigger danger.
- It ignores fitness and blood tests. BMI says nothing about your blood pressure, blood sugar, cholesterol or how active you are.
The best fix is to pair your BMI with a waist measurement. Our waist-to-height ratio tool shows whether your waist is more than half your height, which is a strong warning sign for South Asians. The US CDC adult BMI guidance also stresses that BMI is a screening tool, not a diagnosis.
What your BMI calculator result means: next steps by category
Once the BMI calculator gives you a category, here is what to do next. These steps assume South Asian cut-offs (the default), with the WHO equivalents in brackets.
Underweight (BMI below 18.5)
Being underweight can mean low energy, weak immunity, brittle bones and, in women, irregular periods. It can also signal an underlying problem such as thyroid disease, diabetes, TB, worms or digestive issues.
- See a doctor if you have lost weight without trying, or if you feel tired, dizzy or unwell.
- Eat regular meals and snacks with enough protein: eggs, daal, chana, milk, yoghurt, chicken, fish and nuts.
- Do some strength exercise so the weight you gain is muscle, not just fat.
- Use our calorie and protein calculator and pick a "gain 0.25 kg/week" goal for a steady target.
Healthy weight (BMI 18.5–22.9; WHO 18.5–24.9)
Well done. Your focus now is staying here and keeping your heart and metabolism healthy.
- Aim for at least 150 minutes of moderate activity per week, as recommended in the WHO physical activity guidelines. A brisk 30-minute walk after Maghrib on five days counts.
- Still check your waist. A healthy BMI with a large belly is a risk many South Asians miss.
- Get your blood pressure, sugar and cholesterol checked regularly, especially after 35. Our heart health score brings all of this together.
Overweight (BMI 23.0–27.4; WHO 25.0–29.9)
This is the stage where small changes give big returns. Losing just 5 to 10 percent of your body weight can noticeably improve blood sugar and blood pressure.
- Take our diabetes risk test. It is built on a score validated for South Asians and takes about a minute.
- Swap sugary chai and cold drinks for plain tea, water or lassi without sugar. Cut fried snacks to once or twice a week.
- Fill half your plate with sabzi and salad, a quarter with protein, and a quarter with roti or rice. Choose whole-wheat atta where you can.
- Use the calorie calculator with a "lose 0.25 kg/week" or "lose 0.5 kg/week" goal.
- Check your blood pressure with our blood pressure checker.
Obese (BMI 27.5 and above; WHO 30.0 and above)
Obesity raises the risk of type 2 diabetes, high blood pressure, heart disease, fatty liver, joint pain, sleep apnoea and some cancers. The good news is that steady, realistic changes make a real difference, and you do not have to do it alone.
- Book a visit with your doctor. Ask for a fasting blood sugar or HbA1c test, a cholesterol test and a blood pressure check.
- Ask about a referral to a dietitian who understands desi food. Crash diets rarely last.
- Start moving at a level that suits you: walking, swimming or cycling are easy on the joints.
- Aim for a slow, steady loss of about 0.5 kg a week. The WHO healthy diet fact sheet is a good, simple guide to what to eat more and less of.
Seek urgent care (call 1122 or 115 in Pakistan, or your local emergency number) if you ever have chest pain, severe breathlessness, sudden weakness or numbness, or confusion.
Building a healthy daily routine
A healthy BMI comes from habits you can keep for years, not from quick fixes. Walk wherever you can, take the stairs, sleep 7 to 9 hours, drink enough water in the summer heat, and keep processed and fried foods for special occasions.
Many of our customers like to add a simple ritual to their mornings as part of an overall wellness routine, for example our pure Himalayan shilajit resin with warm water. Supplements are not a weight-loss tool and do not change your BMI. If you take any medication or have a health condition, speak with your doctor before starting any supplement. For gym-goers, our guide to shilajit and gym training explains how people fit it into a training routine.
Want to check more than your weight? Visit our free health calculators hub to find all nine tools in one place, from waist-to-height ratio to heart health.
How often should you use a BMI calculator?
For most adults, checking your BMI every one to three months is plenty. Weight goes up and down by a kilo or two each day because of water, salt and food, so do not panic over daily changes.
If you are actively losing or gaining weight, weigh yourself once a week on the same scale, at the same time of day. Re-run the BMI calculator each month and watch the trend, not the single number. Pair it with a monthly waist measurement for the clearest picture of your progress.
Disclaimer
This BMI calculator and article are for general education only. They are not a medical diagnosis and do not replace advice from a qualified doctor. BMI is a screening tool with known limitations. If you are worried about your weight, or have symptoms or a health condition, please consult a qualified healthcare professional.
