BMI Calculator، Find Your Healthy Weight Range Accurately

BMI is the most widely used global measure for evaluating weight relative to height. This tool calculates your BMI and healthy weight range, and places you within the categories defined by the World Health Organization (WHO).

How the Calculator Works

The core formula:

BMI = weight (kg) ÷ (height in meters)²

Example: height 170 cm (1.70 m), weight 70 kg:

• BMI = 70 ÷ (1.7 × 1.7) = 70 ÷ 2.89 = 24.2
• Category: healthy weight

WHO Standard Categories

| BMI | Category | Risk Level | |---|---|---| | < 18.5 | Underweight | Elevated | | 18.5 – 24.9 | Healthy weight | Low | | 25 – 29.9 | Overweight | Elevated | | 30 – 34.9 | Obesity class I | High | | 35 – 39.9 | Obesity class II | Very high | | ≥ 40 | Obesity class III | Severe |

Source: World Health Organization، BMI Classification.

Ideal Weight for Your Height

To calculate the healthy weight range:

• Lower bound = 18.5 × (height in meters)²
• Upper bound = 24.9 × (height in meters)²

Quick reference:

| Height | Healthy Weight (kg) | |---|---| | 150 cm | 42 – 56 | | 160 cm | 47 – 64 | | 170 cm | 53 – 72 | | 180 cm | 60 – 80 | | 190 cm | 67 – 90 |

Health Risks of Weight Outside the Healthy Range

Overweight (BMI 25-29.9)

• Rising blood pressure
• Early insulin resistance
• Elevated cholesterol

Obesity (BMI 30+)

• Type 2 diabetes: 3× the risk
• Heart disease: double the risk
• Stroke
• Certain cancers (colon, breast, uterine)
• Joint problems (especially the knees)
• Sleep apnea
• Fatty liver disease

Sources: CDC، Adult Obesity Facts · Harvard T.H. Chan، Healthy Weight.

Underweight (BMI < 18.5)

• Weakened immunity
• Osteoporosis
• Fertility issues
• Anemia
• Malnutrition

When BMI Is Misleading

BMI is an approximate measure، it cannot distinguish between:

• Muscle and fat (athletes may register as overweight despite being healthy)
• Fat distribution (abdominal fat is more dangerous than fat on the limbs)
• Age (older adults may need a slightly higher BMI)

For a sharper assessment, use:

| Measure | What It Captures | |---|---| | Body-fat percentage | The most accurate body composition read | | Waist circumference | Abdominal fat accumulation (risk marker) | | Waist-to-hip ratio | Fat distribution (WHR) | | Skinfold measurement | Subcutaneous fat percentage | | DEXA scan | Precise clinical body composition |

Healthy waist circumference:

• Men: under 94 cm (elevated risk above 102)
• Women: under 80 cm (elevated risk above 88)

How to Reach a Healthy Weight

Weight-Loss Plan (BMI above 25)

1. Caloric deficit: eat 300–500 calories below your daily need
2. Adequate protein: 1.6 – 2.2 g per kilogram of body weight
3. Resistance training: 2-3 sessions per week to protect muscle
4. Cardio: 150 minutes of moderate activity weekly (WHO)
5. Sleep: 7-9 hours nightly (poor sleep drives hunger)
6. Water: 2-3 liters daily

Safe rate of loss: 0.5 – 1 kg per week. Faster than that costs muscle.

Weight-Gain Plan (BMI below 18.5)

1. Caloric surplus: 300–500 calories above your daily need
2. Balanced protein and carbohydrates
3. Resistance training: focused work to build muscle
4. 3 meals plus 2 snacks
5. Healthy fat sources: nuts, avocado, olive oil

Before Starting Any Diet

1. See a doctor if you have any chronic condition
2. Get baseline blood work (glucose, thyroid, vitamin D, iron)
3. Skip crash diets (they burn muscle and rebound fast)
4. Weigh yourself weekly under the same conditions
5. Measure your waist monthly، often more telling than the scale

Sources

• World Health Organization، Obesity and Overweight
• Harvard T.H. Chan، Nutrition Source: Healthy Weight
• NIH NHLBI، BMI Calculator Tools
• CDC، Adult BMI
• Harvard T.H. Chan School of Public Health، Healthy Weight

Medical disclaimer: This tool is for guidance only. For medical diagnosis and personalized diet or exercise plans, consult a doctor or a certified dietitian.

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