Free BMI Calculator — Body Mass Index with Body Fat, BMR & TDEE (2026)

Calculate your BMI instantly in metric or imperial units. Get your WHO category, healthy weight range, estimated body fat (Deurenberg), BMR (Mifflin-St Jeor), TDEE with 5 activity levels, and ideal weight from 4 formulas. Includes WHO Asia-Pacific cutoffs for Indian and South Asian populations.

Asian BMI cutoffs

Your Details

Age (years)

Gender

Weight (kg)

Height (cm)

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Enter your age, gender, weight, and height above

Your BMI and all health metrics will appear instantly

BMI is a screening tool, not a diagnostic measure. It does not account for muscle mass, bone density, age, ethnicity, or fat distribution. Always consult a qualified healthcare professional for medical advice.

Complete BMI Analysis

Instant BMI score with a visual color-coded gauge, WHO category, risk level, BMI Prime, Ponderal Index, and exact healthy weight range for your height. Metric and imperial units supported.

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Asian BMI Cutoffs

Toggle WHO Asia-Pacific cutoffs recommended for South Asian and East Asian populations. Overweight starts at 23 and obese at 27.5 — clinically relevant for Indians, as we carry more visceral fat at any given BMI.

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Body Fat Estimation

Estimates body fat percentage using the Deurenberg formula (BMI + age + gender). Also shows estimated fat mass and lean mass in kilograms.

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BMR & TDEE Calculator

Calculates your Basal Metabolic Rate using the Mifflin-St Jeor equation (most validated formula). Select your activity level to get your daily calorie target — and maintenance, loss, and gain targets.

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Ideal Weight — 4 Formulas

Compares four established ideal weight formulas (Hamwi, Devine, Robinson, Miller) side by side with your current weight difference. Shows results in both kg and lbs.

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BMI History Tracking

Save up to 10 BMI readings over time to track your progress. Stored in your browser (no account needed). Copy full results as formatted text to share with your doctor.

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BMI Categories and Associated Health Risks

WHO classifies BMI into eight categories, each associated with progressively different health risk profiles. The thresholds were established based on mortality and morbidity data from large epidemiological studies conducted primarily in European and North American populations.

BMI Range	Category	Risk Level	Key Health Concerns
< 16.0	Severely Underweight	Very High	Organ failure, infertility, immunodeficiency, osteoporosis
16.0–17.9	Moderately Underweight	High	Nutritional deficiencies, low bone density, anemia
18.0–18.4	Mildly Underweight	Elevated	Fatigue, increased infection susceptibility
18.5–24.9	Normal Weight	Low	Lowest all-cause mortality range
25.0–29.9	Overweight	Moderate	Hypertension, prediabetes, sleep problems, joint strain
30.0–34.9	Obese Class I	High	Type 2 diabetes, cardiovascular disease, sleep apnea
35.0–39.9	Obese Class II	Very High	Stroke, heart failure, certain cancers, severe mobility issues
≥ 40.0	Obese Class III	Extremely High	Morbid obesity — life expectancy reduced by 6–14 years

Asia-Pacific WHO Cutoffs (India, China, Japan, Korea)

For South Asian and East Asian populations, WHO recommends lower action thresholds: Overweight starts at BMI 23.0 and Obese at BMI 27.5. Indian ICMR guidelines align with these lower cutoffs because Indians tend to have higher visceral adiposity (abdominal fat around internal organs) at any given BMI compared to European populations. A 2011 study in The Lancet found that Indians had higher diabetes prevalence at BMI 22–24 than Europeans at BMI 30.

Why BMI Has Limitations — and What to Use Instead

BMI was designed as a population statistics tool in the 19th century — not as a clinical diagnostic for individuals. It has several well-documented limitations that make it unreliable for specific groups:

Athletes and muscular people

Muscle is denser than fat. A person with 10% body fat and 80 kg of lean mass may have a BMI of 27 — classified as 'overweight' — despite being in excellent health. Professional sportspeople routinely fall into 'overweight' or even 'obese' BMI categories.

Elderly people

After age 60, people often lose muscle mass (sarcopenia) while gaining fat — a process called sarcopenic obesity. A 70-year-old with a BMI of 23 may have significantly more body fat and less muscle than a 30-year-old with the same BMI. BMI underestimates obesity risk in older adults.

Women during pregnancy

BMI is not a valid health indicator during pregnancy. Weight gain during pregnancy is healthy and necessary. Pre-pregnancy BMI is used for obstetric planning, but current BMI while pregnant has no useful clinical interpretation for obesity screening.

Short stature (under 5 feet)

BMI systematically overestimates adiposity in shorter individuals. The Ponderal Index (weight ÷ height³) is more appropriate for people at height extremes, which is why it is included in this calculator. Research also suggests waist-to-height ratio (below 0.5) is a better predictor for short people.

Better alternatives for individual health assessment include waist circumference (above 90 cm for Indian men and 80 cm for Indian women indicates high visceral fat risk), waist-to-height ratio (keep below 0.5), and body fat percentage measured by DEXA, bioelectrical impedance, or skinfold calipers.

Understanding BMR, TDEE, and Daily Calorie Targets

Your BMR is the energy your body burns doing nothing — just keeping your heart beating, lungs breathing, and cells functioning. For most adults, BMR accounts for 60–75% of total daily energy expenditure. TDEE adds the calories burned through movement and exercise on top of BMR.

Activity Level	Activity Factor	Who This Is For
Sedentary	BMR × 1.2	Office worker, little or no exercise, mostly seated all day
Lightly Active	BMR × 1.375	Light walks, yoga, or gym 1–3 days per week
Moderately Active	BMR × 1.55	Cardio or strength training 3–5 days per week, moderately active job
Very Active	BMR × 1.725	Hard exercise 6–7 days per week, or physically demanding job
Extra Active	BMR × 1.9	Twice-daily training, competitive athletes, or construction/labour work

Lose weight

Eat 300–500 kcal below TDEE. A 500 kcal daily deficit creates roughly 0.5 kg/week fat loss. Avoid deficits above 1,000 kcal/day — this causes muscle loss, hormonal disruption, and is unsustainable.

Maintain weight

Eat at your TDEE. Most people underestimate their calorie intake by 20–30%. Tracking for 2–3 weeks with a food diary gives the most accurate picture.

Gain muscle

Eat 200–400 kcal above TDEE alongside resistance training. A slower surplus (lean bulk) minimises fat gain while allowing muscle to develop. Expect 0.25–0.5 kg/week total weight gain.

Healthy Weight Management — What the Evidence Shows

India faces a dual burden of malnutrition: undernutrition in rural populations and rapidly rising overweight and obesity in urban areas. According to the National Family Health Survey (NFHS-5, 2019–21), 24% of women and 23% of men in India are now overweight or obese — up from 20% and 18% just five years earlier. This rise is driven by sedentary lifestyles, ultra-processed food consumption, and disrupted sleep patterns.

Waist circumference matters as much as weight

For Indians, a waist circumference above 90 cm (men) or 80 cm (women) is associated with significantly elevated metabolic risk — independent of BMI. Abdominal fat, not total weight, is the primary driver of insulin resistance and type 2 diabetes in South Asian populations.

Even 5–7% weight loss changes health outcomes

The Diabetes Prevention Program (US, 7,000 participants) showed that a 7% weight loss combined with 150 minutes of weekly exercise reduced type 2 diabetes incidence by 58% in high-risk adults. You do not need to reach your 'ideal weight' to meaningfully reduce health risk.

Muscle mass is undervalued in weight discussions

Studies consistently show that higher skeletal muscle mass is associated with better insulin sensitivity, lower cardiovascular risk, and better long-term outcomes — independent of BMI or body fat. Resistance training (weights, bodyweight exercises) 2–3 times per week is one of the most effective interventions available, regardless of weight loss.

Sleep and stress affect weight more than people realise

Chronic sleep deprivation (under 6 hours) increases ghrelin (hunger hormone) by 28% and decreases leptin (satiety hormone) by 18%, according to a Stanford University study. Chronic stress elevates cortisol, which promotes visceral fat storage. These factors make weight management physiologically harder — they are not failures of willpower.

Frequently Asked Questions

What is BMI and how is it calculated?▼

BMI (Body Mass Index) is calculated by dividing your weight in kilograms by the square of your height in metres: BMI = weight(kg) ÷ height(m)². For example, a person weighing 70 kg and 1.75 m tall has a BMI of 70 ÷ (1.75 × 1.75) = 22.9. The formula was developed by Belgian mathematician Adolphe Quetelet in the 1830s and was adopted by WHO as a population-level obesity screening tool in the 1970s. It requires no equipment, which is why it became the standard metric in clinical and public health settings worldwide.

What are the BMI categories according to WHO?▼

The World Health Organization classifies BMI into these categories: Severely Underweight (below 16.0), Moderately Underweight (16.0–16.9), Mildly Underweight (17.0–18.4), Normal Weight (18.5–24.9), Overweight/Pre-obese (25.0–29.9), Obese Class I — Moderate (30.0–34.9), Obese Class II — Severe (35.0–39.9), and Obese Class III — Very Severe (40.0 and above). These thresholds were set based on statistical associations between BMI and health outcomes in large population studies.

What are the BMI cutoffs for Indian and Asian populations?▼

In 2004, WHO convened an expert panel that reviewed evidence specifically for Asian populations, including Indians. The panel found that Asians develop obesity-related health risks (type 2 diabetes, hypertension, cardiovascular disease) at lower BMI values than Western populations. The recommended Asia-Pacific cutoffs are: Underweight (below 18.5), Normal (18.5–22.9), Overweight (23.0–27.4), and Obese (27.5 and above). Studies have shown that Indians in particular carry more visceral (abdominal) fat at any given BMI compared to European populations, making these lower thresholds clinically relevant in India.

Is BMI accurate for athletes and people with high muscle mass?▼

No — BMI is a poor indicator of health for people with high muscle mass. A professional weightlifter or rugby player may have a BMI of 28–32 (classified as 'overweight' or 'obese') while having very low body fat. This is because BMI cannot distinguish between fat mass and lean mass. The formula was designed for population-level statistics, not individual health assessment. For athletes, body fat percentage measured via DEXA scan, skinfold calipers, or bioelectrical impedance is a far more accurate metric.

What is BMI Prime and what does it mean?▼

BMI Prime is your BMI divided by 25 (the upper limit of the Normal range). A BMI Prime of 1.0 means your BMI is exactly 25. A value below 1.0 means you are below the overweight threshold, and above 1.0 means you are in the overweight or obese range. BMI Prime is useful because it gives an immediate sense of how far you are from the optimal upper boundary — a BMI Prime of 1.2 tells you instantly that you are 20% above the upper Normal limit, which is easier to interpret than comparing raw BMI numbers.

What is the Ponderal Index and how is it different from BMI?▼

The Ponderal Index (PI) is calculated as weight(kg) ÷ height(m)³, in contrast to BMI which uses height squared. PI tends to perform better for very tall and very short people because body weight scales more closely with the cube of height than the square. For adults, the normal Ponderal Index range is approximately 11–14 kg/m³. PI is less commonly used in clinical practice than BMI but is considered more accurate for individuals at the extremes of height, and is often used in neonatal medicine to assess newborn proportionality.

How is the body fat percentage estimated from BMI?▼

This calculator uses the Deurenberg formula (1991), which estimates body fat percentage from BMI, age, and gender: Body Fat% = (1.20 × BMI) + (0.23 × Age) − (10.8 × Sex) − 5.4, where Sex = 1 for males and 0 for females. This formula has a standard error of about 3–5%, which is acceptable for general screening but not clinical precision. For accurate body fat measurement, DEXA scanning is the gold standard, followed by hydrostatic weighing, then skinfold caliper measurements.

What is BMR and how is it calculated?▼

BMR (Basal Metabolic Rate) is the number of calories your body needs to maintain basic functions at rest — breathing, circulation, cell production, and temperature regulation. This calculator uses the Mifflin-St Jeor equation (1990), which is considered the most accurate formula for most people: For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161. A 2005 meta-analysis found the Mifflin-St Jeor formula predicted measured BMR within 10% for most people, outperforming the older Harris-Benedict equation.

What is TDEE and how should I use it?▼

TDEE (Total Daily Energy Expenditure) is your total calorie burn over a full day, accounting for your activity level. It is calculated as BMR × Activity Factor: Sedentary (desk job) × 1.2, Lightly Active (exercise 1–3 days/week) × 1.375, Moderately Active (exercise 3–5 days/week) × 1.55, Very Active (hard exercise 6–7 days/week) × 1.725, Extra Active (twice-daily training) × 1.9. To lose weight, eat 300–500 kcal below TDEE. To gain weight, eat 300–500 kcal above. To maintain weight, eat at TDEE. Most people underestimate their TDEE by 20–30%, which is a primary reason weight loss efforts stall.

What are the four ideal weight formulas and which is most accurate?▼

The four most cited ideal weight formulas are: Hamwi (1964) — most commonly used in clinical practice in the US; Devine (1974) — developed for pharmacokinetic drug dosing, widely used in hospitals; Robinson (1983) — a refinement of Devine based on a larger dataset; Miller (1983) — another Devine refinement, tends to produce slightly higher ideal weights. None of these formulas accounts for gender, ethnicity, muscle mass, or age beyond adulthood. They were designed to provide a rough clinical benchmark, not a prescriptive target. Research suggests that BMI 20–22 (upper half of the Normal range) is associated with the lowest all-cause mortality in most populations.

Should I use BMI to track my children's weight?▼

Children's BMI is calculated the same way (weight ÷ height²) but is interpreted differently. Instead of fixed thresholds, paediatricians use age- and sex-specific percentile charts (CDC or WHO growth charts). A BMI below the 5th percentile is considered underweight, 5th–84th percentile is healthy weight, 85th–94th percentile is overweight, and at or above the 95th percentile is obese. This calculator is designed for adults (18+) and should not be used for children without converting to percentile interpretation.

I have a normal BMI but a large waist. Should I be concerned?▼

Yes — waist circumference is an independent risk factor for metabolic disease, separate from BMI. Visceral fat (fat stored around internal organs, indicated by a large waist) is far more metabolically dangerous than subcutaneous fat (fat under the skin). High-risk thresholds according to WHO are: men > 102 cm (40 inches), women > 88 cm (35 inches). For Asian populations: men > 90 cm (35 inches), women > 80 cm (31 inches). A person with a normal BMI but a high waist-to-height ratio (above 0.5) has a significantly elevated risk of type 2 diabetes and cardiovascular disease compared to someone with the same BMI but a smaller waist.

Free BMI Calculator — Body Mass Index with Body Fat, BMR & TDEE (2026)

Your Details

Complete BMI Analysis

Asian BMI Cutoffs

Body Fat Estimation

BMR & TDEE Calculator

Ideal Weight — 4 Formulas

BMI History Tracking

Related Tools

BMI Categories and Associated Health Risks

Asia-Pacific WHO Cutoffs (India, China, Japan, Korea)

Why BMI Has Limitations — and What to Use Instead

Athletes and muscular people

Elderly people

Women during pregnancy

Short stature (under 5 feet)

Understanding BMR, TDEE, and Daily Calorie Targets

Lose weight

Maintain weight

Gain muscle

Healthy Weight Management — What the Evidence Shows

Waist circumference matters as much as weight

Even 5–7% weight loss changes health outcomes

Muscle mass is undervalued in weight discussions

Sleep and stress affect weight more than people realise

Frequently Asked Questions

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