Body Mass Index (BMI) is a number calculated from your height and weight that indicates whether you are in a healthy weight range. It is the most widely used screening tool for weight categories — underweight, normal, overweight, and obese.
BMI is a useful screening tool but does not directly measure body fat. Athletes with high muscle mass may have a high BMI but low body fat. Always interpret BMI alongside other health indicators.
How Ideal Body Weight Is Calculated
This calculator uses the Devine formula (1974), one of the most widely used and clinically validated ideal weight formulas:
Devine Formula:
Male ideal weight = 50 kg + 2.3 kg per inch over 5 ft
Female ideal weight = 45.5 kg + 2.3 kg per inch over 5 ft
The "ideal weight" is a reference point, not a target. A healthy weight range — typically BMI 18.5–24.9 — is more practical for most people. Body frame size (small, medium, large) adjusts this range by ±10%.
Other Ideal Weight Formulas
Several validated formulas exist. Hamwi, Robinson, Miller, and Peterson formulas give slightly different values, all typically within 5 kg of each other for average-height individuals. The Devine formula is most commonly used in clinical settings and pharmaceutical dosing.
Important: Ideal weight is a guideline, not a medical target. Factors including muscle mass, bone density, age, ethnicity, and overall metabolic health matter more than any single number on a scale. Consult a doctor or dietitian for personalised guidance.
Frequently Asked Questions
BMI is a useful population-level screening tool with known limitations. It does not distinguish between muscle and fat mass — a muscular athlete may be classified "overweight" despite having low body fat. It also does not account for fat distribution (belly fat is more dangerous than hip fat). Use BMI alongside waist circumference, waist-to-hip ratio, and metabolic markers for a fuller picture.
Health authorities including the CDC, NHS, and WHO recommend losing 0.5–1 kg (1–2 lbs) per week as a safe, sustainable rate. This requires a daily calorie deficit of approximately 500–1,000 kcal. Faster weight loss risks muscle loss, nutritional deficiencies, and metabolic adaptation.
A kilogram of muscle and a kilogram of fat both weigh exactly one kilogram. However, muscle is denser — it takes up about 20% less space in the body than the same weight of fat. This means a muscular person can weigh more yet look leaner than a less muscular person of the same height and weight on the scale.
This calculator uses the BMI-based body fat estimation formula developed by Deurenberg et al. (1991): BF% = (1.20 × BMI) + (0.23 × age) − (10.8 × sex) − 5.4 (where sex = 1 for male, 0 for female). This is an estimate only. DEXA scan, hydrostatic weighing, or skinfold calipers provide more accurate measurements.
Total Daily Energy Expenditure (TDEE) is the total calories your body burns in a day — including basal metabolism, physical activity, and digesting food. It is calculated using the Mifflin–St Jeor equation for BMR (Basal Metabolic Rate), then multiplied by an activity factor. Your TDEE is the calorie level at which your weight stays stable. Eat below it to lose weight; above it to gain.
Yes. The WHO and many Asian health bodies recommend lower BMI cut-off points for Asian populations: overweight starts at BMI 23 (vs. 25 for Western standards), and obese at BMI 27.5 (vs. 30). This is because research shows Asian people tend to have higher body fat percentages and greater visceral fat at the same BMI compared to White European populations, leading to higher health risks at lower BMI values.