You're in the healthy range! Maintain it with regular exercise.
BMI Scale
UnderweightNormalOverweightObese
Ideal weight for 170 cm
53.5 – 72.0 kg
💪 Health tool
What is your body mass index?
Enter your weight and height to instantly calculate your BMI, see your health category, ideal weight range, and personalised health insight. Supports both cm and feet/inches.
Enter your height in cm or switch to feet/inches using the toggle.
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Click calculate
Hit Calculate instantly to get your BMI score.
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Read your result
See your BMI category, ideal weight range, a visual BMI scale, and a personalised health tip.
Why use this calculator?
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Health screening
BMI is the most widely used first-level health screening tool used by doctors, insurance companies, and fitness programs.
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Set a weight goal
Use the ideal weight range to set a realistic target weight for your height before starting a diet or exercise plan.
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Track progress over time
Recalculate your BMI monthly as you work on your health goals to see measurable progress.
How BMI is calculated — formula and example
BMI is the most widely used initial screening tool in medicine because it is fast, universal, and reasonably predictive at population level. A BMI above 25 correlates with higher risk of type 2 diabetes, hypertension, heart disease, and joint problems. A BMI below 18.5 is associated with nutritional deficiencies, anaemia, and reduced immunity. This is why BMI is used for everything from school health checks to insurance underwriting and surgical risk assessments.
The most important limitation of BMI is that it cannot distinguish muscle from fat. A professional athlete or bodybuilder can have a BMI of 28–30 (technically overweight) with excellent health, while a sedentary person with a BMI of 23 can have high visceral fat and poor metabolic health. This is why doctors use BMI alongside waist circumference (>90 cm for men, >80 cm for women is a risk flag in Indians), body fat percentage, blood lipids, and blood sugar to form a complete picture.
For Indian adults specifically, research suggests that metabolic risk starts at lower BMI values than the standard WHO thresholds. The Indian Council of Medical Research (ICMR) and several studies suggest using 23 as the overweight cutoff and 27.5 as the obese cutoff for Indians. This is because Indians tend to have higher body fat percentages and more visceral fat at the same BMI compared to European populations. Check with your doctor if your BMI is between 23 and 25, as clinical Indian guidelines may classify this as overweight.
Formula
BMI = Weight (kg) ÷ [Height (m)]²
Weight is in kilograms. Height must be converted to metres before squaring (e.g., 170 cm = 1.70 m). The resulting BMI score is then classified: Below 18.5 = Underweight, 18.5–24.9 = Normal weight, 25–29.9 = Overweight, 30 and above = Obese. For Indian adults, some health organisations recommend using slightly lower thresholds (23 for overweight, 27.5 for obese) due to differences in body composition.
Worked example
A person weighs 75 kg and is 172 cm tall. Height in metres = 1.72. BMI = 75 ÷ (1.72)² = 75 ÷ 2.9584 = 25.35. This falls in the Overweight category. The ideal weight range for 172 cm height (BMI 18.5–24.9) is approximately 54.7–73.6 kg, suggesting a target weight loss of 1.4–20.3 kg depending on where in the healthy range one aims.
BMI (Body Mass Index) is a numerical value derived from a person's weight and height. It serves as a general indicator of whether an individual has a healthy body weight relative to their height. The value is used to categorise a person as underweight, normal weight, overweight, or obese. These ranges vary slightly based on region and age, and are sometimes divided into subcategories such as severely underweight or very severely obese. While BMI is an imperfect measure of healthy body weight, it remains a widely used first-level screening tool in medicine, fitness, and public health because it is fast, free, and reasonably predictive at a population level.
BMI Table for Adults
The World Health Organization (WHO) recommends the following body weight classifications based on BMI for adults aged 20 and older. These thresholds apply to both men and women.
Classification
BMI range (kg/m²)
Severe Thinness
< 16
Moderate Thinness
16 – 17
Mild Thinness
17 – 18.5
Normal
18.5 – 25
Overweight
25 – 30
Obese Class I
30 – 35
Obese Class II
35 – 40
Obese Class III
> 40
BMI Categories — Visual Overview
The colour bands below represent the major BMI categories as defined by the WHO. Each band shows the BMI range and the associated health classification.
Severe Thinness< 16
Moderate Thinness16 – 17
Mild Thinness17 – 18.5
Normal Weight18.5 – 25
Overweight25 – 30
Obese Class I30 – 35
Obese Class II35 – 40
Obese Class III> 40
BMI Table for Children and Teens (Age 2–20)
The Centers for Disease Control and Prevention (CDC) recommends BMI categorisation for children and teens between age 2 and 20 using percentile ranges rather than fixed BMI values, since healthy BMI varies with age and sex in growing children.
Category
Percentile Range
Underweight
< 5th percentile
Healthy Weight
5th – 85th percentile
At Risk of Overweight
85th – 95th percentile
Overweight
> 95th percentile
Risks Associated with Being Overweight
Being overweight increases the risk of a number of serious diseases and health conditions. The following risks are listed by the Centers for Disease Control and Prevention (CDC):
High blood pressure (hypertension)
Higher levels of LDL cholesterol and triglycerides, lower levels of HDL cholesterol
Type II diabetes
Coronary heart disease
Stroke
Gallbladder disease
Osteoarthritis — joint disease caused by breakdown of joint cartilage
Sleep apnea and breathing problems
Certain cancers (endometrial, breast, colon, kidney, gallbladder, liver)
Mental health conditions such as clinical depression and anxiety
Body pains and difficulty with certain physical functions
Increased risk of mortality compared to those with a healthy BMI
A person should aim to maintain a BMI below 25 kg/m², but should consult their doctor to determine whether lifestyle changes are needed based on their full health profile.
Risks Associated with Being Underweight
Being underweight carries its own set of health risks:
Malnutrition, vitamin deficiencies, and anaemia
Osteoporosis — reduced bone density and increased fracture risk
Decreased immune function
Growth and development issues, particularly in children and teenagers
Reproductive issues in women due to hormonal imbalances
Potential complications during surgery or recovery
Increased risk of mortality compared to those with a healthy BMI
In some cases, being underweight may indicate an underlying condition such as anorexia nervosa. Consult a doctor if you or someone you know is underweight, especially if the cause is not obvious.
Limitations of BMI
BMI is a widely used indicator of healthy body weight, but it has notable limitations. It is only an estimate and cannot account for body composition. Due to the wide variety of body types and differences in muscle mass, bone density, and fat distribution, BMI should be considered alongside other measurements rather than used as the sole method for determining a healthy body weight.
In Adults
BMI cannot fully distinguish between excess body weight and excess body fat. It is further influenced by age, sex, ethnicity, muscle mass, and activity level. According to the CDC:
Older adults tend to have more body fat than younger adults at the same BMI
Women tend to have more body fat than men at an equivalent BMI
Muscular individuals and trained athletes may have higher BMIs due to large muscle mass
In Children and Adolescents
The same factors that limit BMI accuracy in adults also apply to children. Additionally, height and sexual maturation influence BMI and body fat in growing children. BMI is a better indicator of excess body fat for obese children than for overweight children. That said, BMI is fairly indicative of body fat for 90–95% of the population and can be used effectively alongside other measures.
BMI Formula
Below are the equations used for calculating BMI in both the metric (SI) and imperial (USC) systems, using a 5'10", 72.57 kg individual as an example:
Metric (SI) Units
BMI = weight (kg) ÷ height² (m)
= 72.57 ÷ (1.778)² = 72.57 ÷ 3.161 = 22.96
Imperial (USC) Units
BMI = 703 × weight (lbs) ÷ height² (in)
= 703 × 160 ÷ (70)² = 112,480 ÷ 4,900 = 22.96
BMI Prime
BMI Prime is the ratio of a person's measured BMI to the upper limit of the normal BMI range (25 kg/m² as defined by the WHO). It is a dimensionless value that allows quick assessment of how far a person's BMI deviates from the normal upper limit.
The Ponderal Index (PI) is similar to BMI in that it measures the leanness or corpulence of a person based on height and weight. The key difference is that PI cubes the height rather than squaring it. While BMI can be a useful tool for large populations, it is less reliable for very tall or very short individuals. The PI is more reliable at the extremes of the height spectrum.
Metric (SI) Units
PI = weight (kg) ÷ height³ (m)
= 72.57 ÷ (1.778)³ = 72.57 ÷ 5.62 = 12.9
Imperial (USC) Units
PI = height (in) ÷ ∛weight (lbs)
= 70 ÷ ∛160 = 70 ÷ 5.43 = 12.9
Frequently asked questions
Only on Calculator Planet
What makes this BMI calculator different
Most BMI calculators give you a number and a category. Ours gives you a live visual BMI scale with a moving needle, a colour-coded health card with a personalised tip, your ideal weight range for your exact height, and a cm/feet toggle so you never have to convert units manually.
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Live BMI scale needle
A colour-coded scale (blue → green → amber → red) with a needle that moves in real time as you adjust your weight or height.
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cm / feet–inches toggle
Switch between centimetres and feet/inches with one tap. No manual conversion needed — the BMI recalculates instantly.
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Ideal weight range
Shows the exact healthy weight range (BMI 18.5–24.9) for your specific height in kg, so you have a concrete target.
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Personalised health tip
Each BMI category shows a different actionable tip — not a generic message, but one matched to your specific result.
BMI categories — what each colour zone means
The BMI scale uses four colour zones. Here is what each one means and what the calculator shows for each:
🥗 Tip: Consider a balanced diet with more protein and healthy calories.
Normal weight18.5 – 24.9
⚠️ Risk: Lowest risk of weight-related conditions
💪 Tip: You're in the healthy range! Maintain it with regular exercise.
Overweight25 – 29.9
⚠️ Risk: Elevated risk of diabetes, hypertension, joint issues
🏃 Tip: 30 minutes of walking daily can make a big difference.
Obese30 and above
⚠️ Risk: High risk of heart disease, type 2 diabetes, sleep apnoea
❤️ Tip: Small daily changes — less sugar, more movement — add up fast.
Indian BMI thresholds are lower
The Indian Council of Medical Research (ICMR) recommends using 23 as the overweight cutoff and 27.5 as the obese cutoff for Indian adults, because Indians tend to carry more visceral fat at the same BMI compared to Western populations. If your BMI is between 23 and 25, consult your doctor.
Ideal weight by height — quick reference table
The calculator shows your ideal weight range live. Here is the full reference for common heights:
