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Complete weight management tool with unit converter (kg/lbs/stone), BMI calculator, ideal weight finder, personalized weight loss planner & progress tracker. Free & instant results!
Convert between different weight units instantly
Quick reference for converting between common weight units. These conversion factors are internationally standardized:
| From | To | Multiply By | Example |
|---|---|---|---|
| Kilograms (kg) | Pounds (lbs) | 2.20462 | 70 kg = 154.32 lbs |
| Pounds (lbs) | Kilograms (kg) | 0.453592 | 150 lbs = 68.04 kg |
| Stone (st) | Kilograms (kg) | 6.35029 | 10 st = 63.5 kg |
| Kilograms (kg) | Stone (st) | 0.157473 | 70 kg = 11.02 st |
| Pounds (lbs) | Ounces (oz) | 16 | 5 lbs = 80 oz |
| Kilograms (kg) | Grams (g) | 1000 | 1.5 kg = 1500 g |
| Stone (st) | Pounds (lbs) | 14 | 10 st = 140 lbs |
Body Mass Index (BMI) is a screening tool that estimates body fat based on height and weight. It's calculated by dividing weight in kilograms by the square of height in meters: BMI = weight(kg) / height(m)². Developed by Adolphe Quetelet in the 1830s, BMI is widely used by healthcare professionals as an initial assessment tool. However, it doesn't directly measure body fat percentage and may not accurately reflect health status for athletes, pregnant women, elderly individuals, or those with high muscle mass.
BMI Formula:
BMI = weight (kg) / height² (m²)
Example: 70 kg ÷ (1.75 m)² = 70 ÷ 3.06 = 22.9
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Increased risk of malnutrition |
| 18.5 - 24.9 | Normal Weight | Lowest health risk |
| 25.0 - 29.9 | Overweight | Increased health risk |
| 30.0 - 34.9 | Obese Class I | High health risk |
| 35.0 - 39.9 | Obese Class II | Very high health risk |
| 40.0 and above | Obese Class III | Extremely high health risk |
Note: Healthcare professionals use BMI as one of several assessment tools, not as a sole indicator of health.
This calculator uses five scientifically established formulas to calculate ideal weight, then provides an average recommendation. These formulas were developed by medical researchers and are widely used in clinical settings:
Men: 52 kg + 1.9 kg per inch over 5 feet
Women: 49 kg + 1.7 kg per inch over 5 feet
Example: 5'8" man = 52 + (8 × 1.9) = 67.2 kg
Source: Robinson JD, et al. Am J Clin Nutr. 1983
Men: 56.2 kg + 1.41 kg per inch over 5 feet
Women: 53.1 kg + 1.36 kg per inch over 5 feet
Example: 5'8" man = 56.2 + (8 × 1.41) = 67.48 kg
Men: 50 kg + 2.3 kg per inch over 5 feet
Women: 45.5 kg + 2.3 kg per inch over 5 feet
Originally developed for drug dosing calculations
Source: Devine BJ. Drug Intell Clin Pharm. 1974
Men: 48 kg + 2.7 kg per inch over 5 feet
Women: 45.5 kg + 2.2 kg per inch over 5 feet
Quick estimation method for clinical use
Ideal Weight = 21.5 × height² (m²)
Based on optimal BMI of 21.5 for both genders
Example: 1.75 m tall = 21.5 × (1.75)² = 65.8 kg
According to guidelines from health organizations including the CDC and WHO, a safe and sustainable weight loss rate is 0.5-1 kg (1-2 lbs) per week. This requires a daily calorie deficit of 500-1000 calories. Research indicates that faster weight loss may lead to muscle loss, nutritional deficiencies, gallstones, and is more difficult to maintain long-term. Gradual weight loss allows the body to adapt and helps preserve lean muscle mass.
Calorie Deficit Formula:
1 kg fat = 7,700 calories
To lose 0.5 kg/week: 7,700 ÷ 2 ÷ 7 = 550 cal/day deficit
To lose 1 kg/week: 7,700 ÷ 7 = 1,100 cal/day deficit
These multipliers are based on the Harris-Benedict equation and are used to estimate Total Daily Energy Expenditure (TDEE):
| Activity Level | Description | Multiplier |
|---|---|---|
| Sedentary | Little or no exercise, desk job | BMR × 1.2 |
| Light | Light exercise 1-3 days/week | BMR × 1.375 |
| Moderate | Moderate exercise 3-5 days/week | BMR × 1.55 |
| Active | Hard exercise 6-7 days/week | BMR × 1.725 |
| Very Active | Very hard exercise, physical job | BMR × 1.9 |
Note: These are general guidelines based on health research. Individual needs vary. Consult healthcare professionals for personalized advice.
To convert kilograms to pounds, multiply the weight in kg by 2.20462. For example: 70 kg × 2.20462 = 154.32 lbs. Our calculator performs this conversion instantly along with conversions to stone, grams, and ounces.
BMI (Body Mass Index) is calculated by dividing weight in kilograms by height in meters squared: BMI = weight(kg) / height(m)². For example, a person weighing 70 kg and 1.75 m tall has BMI = 70 / (1.75)² = 22.9, which is in the normal range (18.5-24.9). BMI is a screening tool but doesn't measure body fat directly.
According to health guidelines, a safe weight loss rate is 0.5-1 kg (1-2 lbs) per week, requiring a daily calorie deficit of 500-1000 calories. Faster weight loss may lead to muscle loss and nutritional deficiencies. Consult a healthcare provider before starting any weight loss program.
Calculate Body Mass Index and health category
Calculate daily calorie needs for weight goals
Estimate body fat percentage accurately
Find your ideal weight using 5 formulas
Calculate Basal Metabolic Rate
Calculate mass from density, force & more
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This calculator provides estimates and general information for educational purposes only. It is not intended to replace professional medical advice, diagnosis, or treatment. The calculations are based on established formulas but individual health needs vary significantly.
Always consult with a qualified healthcare provider before:
Note: BMI and other calculations may not accurately reflect health status for athletes, bodybuilders, pregnant women, elderly individuals, children, or people with certain medical conditions. Individual health assessment requires comprehensive evaluation by healthcare professionals including physical examination, medical history, and potentially laboratory tests.
Emergency: If you experience severe symptoms, chest pain, difficulty breathing, or other medical emergencies, seek immediate medical attention.